I have made a pretty concerted effort to lay off the skidding and leg braking lately as I've been working on building distance. Both my upcoming century training ride and the intended 200k brevet are pretty flat so I shouldn't have too much trouble relying on the brake.
I think I am going to go with the single brake for the time being. It got me through recent rides on some pretty massive hills in WI so it should be sufficient for now. I'll revisit the idea of a second brake for longer rides if I find myself wishing I had one at the end of one of these.
Thanks for all the help! It's kinda odd that there isn't really a single web locale for long distance fixed riding (is there?). I'm an ultrarunning vet and could not have done the ultras that I did without a few of the key repositories of ultra info (gear, pacing, nutrition etc). Anyone want to start one?