My Pmax currently sits at 804W.

Also, my regular bike has STIs, but I am building up an old frame and I was thinking of going for downtube shifters just to have something different. Still not convinced it is worth it.

I do need to make some time this winter to work on sprinting technique. Right now more often than not I end up either in the wrong gear or wobbling like crazy or just being unable to get the power down when I try. The few times it has clicked it seems like I can get some decent speed going. Not win a bunch sprint speed, but at least not end 300 meters behind bad, which is usually what happens.