My video of a comparison between diverters and a DIY thing

I installed a Fiskars diverter and a DIY thing, basically a funnel, and it appears due to the design, the diverter looses a lot of the water.  The implications may be different based on your local rain fall, but from when I have done here, the funnel type thing collected a lot more water.
And if you're wondering about overflow, I've since taken care of that.

OK, but the point of the diverter is to keep the barrel from overflowing into your house foundation when the rain comes down fast. If that's not a concern, by all means pipe your downspout directly into the barrel. But I flooded my basement doing that before I bought one of the Fiskars things.

Here's another approach I came up with: https://www.interdepweb.com/drupal7/content/simpler_ultimate_rain_barrels

We flooded the basement in our old home as well with a poorly designed rain catching barrel. the flooding wasnt bad but definitely not good. Our solution was to bring a drain pipe off the top, similar to the spout you have at the bottom but running off the side near the top, that would flow away from the house when the barrel was full. cheap and easy solution.

Ben Stallings wrote:OK, but the point of the diverter is to keep the barrel from overflowing into your house foundation when the rain comes down fast. If that's not a concern, by all means pipe your downspout directly into the barrel. But I flooded my basement doing that before I bought one of the Fiskars things.

Here's another approach I came up with: https://www.interdepweb.com/drupal7/content/simpler_ultimate_rain_barrels

Like your deisgn, but I resorted to something simpler. I bought a 330gal tote. Modified the top cap to accept a 4" drain pipe just as you have it in your design. The bottom drain of the tote I bought an adapter, 90o ell and pipe and set it up as a riser to match the top of the tote. Any excess water flows out the riser off to other parts of the property. The downside is the single point of failure using the tote.