Ron Wanttaja schrieb:

Cockpit access issues and CG, would be my guesses.

I don't think so. Cockpit access is no issue, and the pilot sits pretty
near the CG. But if you take a closer look, the pilot's sight is not
that great, either, at least if you believe that the pilot should be
able to look over his shoulder before turning:
http://de.wikipedia.org/wiki/Bild:Bo208C_HB-UPF_68.jpg

The main disadvantage is the wing spar which prevents a reasonable and
easy accessible luggage room behind the pilot and which limits the whole
design to two seaters.