The Partnavia is not a bad performer on 1 engine. I clocked up 300 hrs in them and had the oppertunity to operate on 1 a few times.
Climbed out at 400fpm, full fuel, 3 pax on board. Would have been within 200kg of MTOW I think from memory.
Not as bad as everyone seems to be suggeting.
They are not that good for your back though, Ouch!!
Bulla