I looked at a Torqueedo a few months ago but the power was insufficient for our dink - there was no way it would get up on plane - we need about 8HP to do that reliably with two aboard.
I'm sure the propane outboard will work great; I don't think anyone can argue against the operational function - propane has been powering engines used on everything from farm combines to forklifts to city busses for many years so the only issue for an outboard is just the convenience difference between gasoline/propane. Certainly it will eliminate any of the gasoline issues associated with clogging carb jets/fuel longevity, spilling fuel, etc. In further thinking about it, the only potential downside really, I guess, is just the fact that gasoline is available literally anywhere/any marina whereas propane is not. But some minimal planning should obviate the issue/concern.
Let us know how you like it, we have been talking about getting a new outboard...