Why not ride a Brooks? I started riding mine when I had a 1.3 mile commute to work, it did break in. BTW I do my current 13.5 mile RT commute with both a B17 narrow and a Flyer on my mountainbike with Nitto All-Rounder bars set maybe an inch above my seat.
I was using the Flyer exclusively (had the B17n on my roadie) but the frame on the Flyer broke and am using the B17n while I wait for a replacement Flyer frame to arrive from Wallbike.
I thought there be a lot of difference, but the differences aren't huge - when I spin at high (110+) RPMs on the Flyer I tend to bounce a bit, on the B17n my pedaling at high RPM is smoother. Going over bumps, the Flyer is nicer - no need to lift off the saddle to absorb them (nice when I'm still half asleep on my ride in).
Honestly, I don't think you would go wrong with either. Of course, if your butt doesn't fit a B17, then all bets are off.