If I'm not mistaken, "market weight" for slaughter hogs was more in the 220-240 lb. range (live weight), at least historically.
Largely, I think, it's going to depend on what you feed them. Last year we raised a group of Large Black/Hampshire crosses. Feeding them a relatively low protein, soy-free, whole grain diet, plus garden culls and forage, they made it to about 200-220 lbs. right at one year. In the past we've raised Mulefoots in a similar way, and they pretty consistently took 14 months to get to 225 lbs. But if we (or you) fed a higher protein ration, they surely ought to get there faster. Amount of feed makes a difference too, of
course. On full feed, hogs will grow more quickly than if they're hand fed a more limited amount.
The upside with a long grow-out period is that it makes for absolutely delicious pork. When everyone else is slaughtering at 5 or 6 or 8 months, there's a noticeable difference in a porker slaughtered earlier.
As for economic concerns, keep in mind that the Large Black is known as a pretty fair grazer. With plentiful forage and a low-protein (and thus low-cost) grain supplement, the longer growout period may be offset so that it's equally profitable.