Once you add JIT and Picasso support then WinUAE is going to wipe the floor with a real Amiga unless you have a LOT of upgrades. I suspect on a high-end PC it will rival or beat PPC accelerators too.
Also, you can use much more modern graphics cards on PCs and WinUAE automatically supports them and passes this benefit onto the Amiga, for 2D stuff anyway.
Personally, getting the accelerator for the A1200 was not about making the Amiga fast. It was about making it fast enough and with enough RAM to easily install software on it and pull ADF files over the network. Trying to get an A1200 to be fast seems kinda silly considering how powerful PCs are now. You can buy a decent PC for how much it would cost for even an 060 card. If you go PowerPC you could build a PC many times more powerful for the same price or cheaper. You would have to REALLY be obsessed to choose the Amiga.
While I love the Amiga dearly I have moved on and can live with XP or Linux for anything serious. Theres not a single thing I can think of where the Amiga would be better than PC, other than playing old Amiga games.
Of course this might change if OS4 ever happens and hardware to support it. But upgrading classic Amigas is not the future, building PCs that run OS4 is. (and when I say PCs I mean whatever hardware you need not necessarily IBM compatible)