Are you going to be racing? Sounds like it but I don't think you said.

LandShark has been building Fillet-brazed frames for a long time and I've never heard of any problems with the method. One of the big benefits of lugged frames is that damaged tubes are easy to replace. Something to think about if this will be a difficult frame to replace. I think the strength issue will have much more to do with your tubing choice.

If you want to talk about things like a few grams here or there and inertia of wheels, take note that cartridge bearings do add drag to the system due to the seals. There is a good amound of debate, but I think it's still accepted that loose ball systems cause less friction for both hubs and BB's.

I have a campy record front hub and a phill in the back. When I've just overhauled it, the front feels much smoother and easier spinning. For daily riding, I overhaul my front hub about once a month. Generally takes about 15min. I definately perfected my overhaul technique on a cheap hub before I touched the campy one though. I quickly found myself wishing I had more loose ball stuff on my bike to overhaul. It gets addictive.