I have an use an A4000. I don't use a Video Toaster thought.
Whilst there aren't specific games for A4000 there are for AGA same as A1200 but with the A4000 you have easy upgrade access to RTG and Sound Cards and there are games and software that take advantage of RTG/AHI.
I had an A4000T but I sold it last year when I was out of work. In fact I sold a lot of my Amiga stuff, I've also had A4000's in after market towers by Elbox such as Power Tower & Mirage Pro.