Not to confuse the OP, Let's make the distinction between gas engines for IMAC and gas engines I use in Pattern. Huge difference in the noise generated. My set-ups are on par to some YS and better than most. It's all in the set-up of the 33cc gas engine.

As far as cost per flight (let's assume an 8 minute flight since that's the electric standard), the YS's will run you about 1$ per 8 minutes (assumes 20% nitro glow). Electrics will run you about 2$ for 8 minutes for good batteries and about 3$ per flight for top of the heap batteries. Gasoline will run you about 10 cents per 8 minutes. Excludes any maintenance for motors/engines.

The Saturn will operate just fine on the YS140 which is less expensive to run than the larger YS's.

The battery comparison considers good and best batteries only which will last about 80 flights on average for the good to about 120 flights for the best. Certainly there are cheaper batteries but their longevity and safety is questionable. BUT for most guys running E-power, cost is not an issue and it isn't unusual for many to have a dozen sets of batteris ready for service.

To me, keeping tabs on all of these takes the fun out of it. I'd much rather take my plane to the field, gas it up, fly the heck out of it (when I am able to) and take it home. The gas engines have proven nearly maintenance free; no plug changes, no rust in the bearings, squeeky clean inside after a 100 hours of operation.