What after Aleph 3, need more juice?

I've a similar system, WP5.1 and Aleph 3 in a medium sized room so I know why you like this combination. I have a number of other amps as well, when I want more power I switch to a BAT VK-200, it really integrates well with the WP's. You should give this a try, they cost about 1650 used (maybe less now that a new model is coming out from BAT), 100 WPC into 8, 200 into 4. And you won't miss the heat buildup that you are used to from the Aleph, the BAT runs very hot. The only thing is that they have balanced only inputs and you need an adaptor if you don't have a balanced pre.

In rereading your post, don't sell the Wilson's! You can get amazing sound, just up the power, they can take it. Also, the Watts are designed to be connected to the Puppy crossover, so you should not biamp them as suggested above, and the manual agrees on this point. I have heard that Krell amps work well with these speakers. I also have Counterpont SA-100 modded by Mike Elliot which works wonders, and which fills the room just as much as the BAT.