I have always been successful in convincing people who think they need a 15" pull length otherwise with guns I made for them. 13 1/2" is pretty well universally good, unless you're really small of stature.
I personally like a little bit longer, like 13 3/4", but it's not that huge a deal (I'm fairly tall with REALLY LONG arms). There's no way I could even handle one at 15"...it would hang up bad in my armpit. I really don't think arm length is the big factor anyway. The comb line and cheekpiece are MUCH more important, and have to be just so. I am a cheekpiece fanatic.