I don't have a dog in this fight, yet, so I figured I'd throw mine in.

All this talk of reliability, statistics, redundant systems, engine
failure, and dying is the perfect place to put in my 2 cents about
using 2 single ignition engines to get a dual everything. Its like
the brakes in your car. Brakes are pretty important right? But, you
don't pay a zillion dollars for single special purpose super reliable
brake system, that you have to have professionally inspected every
year. No, you design a cross coupled redundant system that granny can
drive and say "It pulls to the left", when one of the 2 circuits
fails.

Read all about it at:

http://inline_twin.tripod.com/concept.html

I'm thinking folding props might be better than the CS full feathering
type I'm using now in the model.

There is a guy that was (still is?) flying a push pull power pod sea
plane with a Mazda 13B in back and a Rotax (I think) in front. Talk
about mixing and matching. Maybe he was going for that "disimilar"
idea you see in voting flight control systems on the big 'uns.