Thank you guys!
This is exactly the sort of input I was looking for. I wasn't actually planning on bashing a single into a tri-motor, but for the sake of the discussion, it's an ideal illustration. Besides, come to think of it, bashing a sport type single into a simple non scale tri-motor is probably a good idea. I can use it to familiarize myself with multi-engine operations prior to flying a "bigger investment" scale model.
I'm a fan of 'Golden Age" aircraft, so any scale multi that I build will be from that era. Fortunately, those aircraft usually had generous amounts of wing area and indeed some are even biplanes. Their fabric covered structures and fixed gear also allow for some weight savings as compared to a warbird for example.

I can't help but think that a tri-motor would have an advantage over a twin in an engine out situation. It seems to me that with the loss of an outboard engine, the tri-motor would have less assymetric thrust for the given remaining available power than a twin.
My only experience with multi's so far was rather comical. I was standing on the flight line supervising a student one day, and the fellow next to us who at that time was still a relative newbie himself, was flying a twin for the first time. He had an engine out and the plane went out of control. He yelled that he needed help and jammed the transmitter into my hands! I instinctively closed the throttle and managed to get it straightened out and back to the runway. If it wasn't for the altitude he had at the time, things might not have turned out so well!

Cheers, Nigel