I'm 184cm tall and quite big, I've never found the Saab 340 small or cramped. I don't even recall the lack of headroom as being even the slightest issue when boarding and I've flown in them several times.
I'll take a faster flight time over overhead bin capacity any day (it's not exactly hard to get the baggage out of the hold at a regional airport, is it?) Besides, under the seat worked just fine for me last time I flew one.....