Jim... good thoughts.
Converting to gas has pros and cons with the greatest negative the degradation of power. I've now flown the 1/5 World Models Cub powered by the 90TS on gas running a MAS 14x6 prop. What previously was an overpowered Cub is now a reasonably powered Cub. The plane flies slower than previous... more like a Cub. It does get airborne easily and will easily loop from level flight and pull over the top without concern due to the torque of the longer/lower pitch prop.
I'd probably not recommend converting this engine to gas on anything other than a floater such as the cub. The Cub weights 8.25 lbs... and I suspect that would be around the upper limit for the engine on gas. It requires nearly half throttle to hold altitude albeit that may change when getting the balance back. I've moved the battery back for more testing and am prepared to add tail weight if more aft balance is needed.
Floater planes generally enjoy a six or even less pitch prop because they provide more torque and less speed and they do a much better job of braking to prevent the long landings that floaters sometimes suffer, albeit a prop that will provide significant braking needs to have landing rpms dialed as too much braking action can slow the plane too much.
On a non floater... spark ignition is a good alternative to on board glow but I'd stay with nitro glow fuel to keep the power on an engine like the Saito 90TS. If aerobatics are important... power is not something usually traded off... so stay with glow nitro fuel.
Gas has its advantages however, fuel cost are 1/10. On this plane, a flight will cost 10 cents compared to a dollar. Clean up is much easier, requiring 20 sec with a single alcohol wipe compared to several paper towels and 3-5 minutes. Fuel is readily available.and solves the problem for some areas where glow fuel is getting hard to obtain. Spark ignition is in my opinion more reliable than glow ignition. I've now about eighty flights on Saito conversions to gas with zero dead sticks.