Julian,
I will give you my own two cents about chippers.
Depending on your own circumstances and money you want to spend, Yes, a chipper may be a worthy investment. But before you go out and buy one, consider its cost and purpose. Personally, I chip once per year in the mid-spring. At this time I go out and do a bunch of trimming, largely along an almost 800' living fence in addition to woods alongside my back yard, occasional woody debris from my woods, and from my neighbors. Typically, one neighbor and I will split the cost of renting a chipper and chip up small mountains of wood chips all in one weekend. I will typically save a lot of my trimmed brush someplace obscure throughout the year until chipping day in which case we do it all at once. From my own experience (and if someone else either agrees or disagrees with this statement, please let me know because I am interested in how this works with others) I have found that the official rating of a chipper is mostly a fiction and is actually only good for about half the official rating. I know that statement was clear as mud, but here is another way of looking at it. I used to rent a 6 inch chipper. I could feed that chipper debris up to 6 inches in diameter. Any larger and it would not physically fit into the feeder. While it was technically possible to chip up a 6 inch branch or tree trunk, I could never do this very long and certainly could not keep it up all day. Invariably, even though virtually all of my chipping was 6 inches or less, after feeding large volumes of wood over about an hour, the chipper would break. Specifically, the roller feeder that physically draws the brush and debris into the chipper housing just quit and would only run in reverse. No mater what I did, the feeder would not work and I would then be done chipping. I really tried to get the chipper to work. I would go through the manual, I would make sure none of the numerous safety devices were tripped--everything I could do including partially disassembling the rental unit and nothing I could do would make that chipper work again.
What I started doing after a couple of years of rental machines that were supposedly new and in good condition that would not chip reliable was to rent a 12 inch chipper for the job. A 6 inch chipper was $150/day and a 12 inch chipper was $300/day, but what a difference that 12 inch chipper made! Firstly, the 12 inch chipper could take much, much more material than the 6 inch chipper, and chip it all up much faster. Secondly, since we were chipping material no where near the rated capacity, the chipper never broke down. I can't tell you how exhausting it was to be feeding material into the 6 inch chipper only to have it spit that material back out and try again. With the 12 inch chipper, once the wood went in the chipper, it got chipped up. It was simply a much more reliable process and by experience I have found that the 12 inch chipper is well worth the extra expense.
So by now you may be thinking "that's great, but what about buying a chipper?" A good chipper is not a cheap proposition. In my own case, I have absolutely no problem cutting/pruning/etc. and leaving the material in an out of the way spot for my once-annual chipping weekend. I spend $300/year for all of my chipping requirements so for my case, renting a large, really heavy duty chipper with and in-feed roller is much cheaper than buying a similar unit and certainly easier than storing, maintaining, etc.
But perhaps you are not in my situation. Some people do not have the luxury of just cutting stuff down and leaving it out of the way. For some people, any downed brush would be unsightly and possibly violate local covenants or even local laws. In this case, if you think you are going to be trimming up quite a lot of brush and need it chipped quickly and you will be doing this often, then by all means, a chipper may be worth the costs. I will offer up a warning though--don't buy cheap. Chippers are machines that are practically designed to damage themselves. There are a lot of mechanical forces a work and based on personal experience I have found that a cheapo machine is really more expensive in the (sometimes not so terribly) long run. There are a couple of brands that I might buy from if I really got serious about owning a chipper. One brand makes an 8 inch chipper that looks (and has good reviews) like it might do the job for me. But I have two great big factors holding me back. Firstly the practical. That particular chipper is a 3 point mounted, PTO powered chipper. That means it needs to be attached to my tractor to work. In turn, that means I can not use my tractor for dragging around branches while I am chipping--a real problem in my case as when I am doing my chipper weekend, I would much rather let the tractor do the work of dragging around debris than me doing it manually. Even with the tractor doing the bulk of the work, one day of chipping is surprisingly exhausting. My second major gripe about owning a chipper is simple cost. That great 8 inch chipper will set me back by about $3000. This means I would have to use it for 10 years to get a payback on the machine. For my own purposes, I would rather rent a (better) chipper and get a grapple for my tractor to really make moving debris around easier than to own an acceptable chipper that denies me the use of the tractor for other purposes. To make things more complicated, you could go so far as to buy a self powered chipper, but in that case you would then be buying the additional cost of the engine, and have to store it, and have to perform maintenance. And if it breaks, guess who gets to fix it.
Julian, you are absolutely right that wood chips and mulch can in fact be a tremendous boon to your gardening experience. I am in the process of converting all of my gardening beds over to raised beds full of wood chips inoculated with wine cap mushrooms in order to make my own mushroom
compost super soil. I personally strongly advocate for using wood chips as mulch or as compost (or both). And maybe you are not in a position like myself where I can leave branches laying about out of sight for a year. Perhaps a chipper is worth your money. However, based on my experience/frustration with wood chippers, I personally would much rather rent them and let someone else fix them. I have not yet broken a 12 inch chipper, but I shudder at the thought of what one of those machines cost. Ultimately, you do what you think is in your best interest, but for myself, I will rent them.
I hope this is helpful, and if I let anything unclear, by all means, let me know and I will try to clarify.
Eric