I don't get the weight weenies. Look at the actual change in the total bike and rider weight TOGETHER. A one pound increase on a combined bike and rider weight of 200lbs is NOTHING! You are not spinning these tires up to high rpms so even the energy loss of due to acclerating the extra mass isn't super significant. Keep in mind how much less energy is lost due to the higher efficiency of the BAs if you have rough roads and it isn't funny.

I have crappy roads where I live and the BAs are a treat to ride on and on most courses near my house I am faster on my BAs than my Stelvios. If I lived in Florida it would not be the case but we have a lot of frost damaged roads. I can't ride a Stelvios through grass either and the BAs I easily can.

I used to think (wrongly) that my BAs were a lot slower than my Stelvios because the bike felt a little less snappy. Riding on my test course at an average pace told a different story. My roll-down testing likewise showed that what may feel faster may not actually be. The Stelvios ALWAYS felt faster but that was in part due to the amount of road vibration I felt so they seemed more responsive. Maybe if I had to stop and start every 100 feet then the extra effort to spin up the BAs might almost matter. In the real world I can diet and shave off more weight than the BAs add.

If you are building a track bike, then don't buy the BAs. The vast majority of the people who try them love them. One thing almost all tire companies agree on, higher volume tires are more efficient than lower volume tires when it comes to rolling resistance.

The downside is higher volume normally means adverse impacts on the aerodynamic aspect of the tires. So if you are fast (20mph+) then this might actually matter a little bit when you are up in the speed range where aerodynamic drage becomes the predominant force you must overcome. On my Swift I am not worrying about that too much, on my recumbent it is a different story.