I've used both Sustained Energy and Perpetuem (lovingly known as Perpetuity in our house) and like them both. The thing I like the best is that I am not usually hungry after I finish riding if I have followed the regimen properly. I always do a super concentrate and just take a small sip followed with plain water. My very long ride routine is to start at 15 minutes into the ride with a slug of Perpetuity or SE, gel on the 30 and 0, and Perpetuity on the 15 and 45 (that is, intake something every 15 minutes). My buddy is a 20 minute gal. You just have to experiment.

But ya, don't try it now!