Well of course the whole thing is rather comical because the next step up is real FIRE meaning STEAM! but as well all know I think when you turn off the burner it goes out...pop and thats it, 10 minutes later and its cold, no fire risk.......
Well Chris I was thinking of automatic block signalling (several trains following one another). I know sounds crazy in larger scales but I have seen it working in gauge 1 over several acres and implemented it in O gauge in an acre.
I've got a couple of live steamers with radio control: now in well-protected (I hope) storage.
Didn't suit the tight radii on my previous garden line (though withing their spec. They ran, but...)
And didn't adequately handle the unavoidable gradients on my current one.
But if you're up to acres, why not buy a small real railway?
More realistically, with the equivalent salary to 20 years ago, and the price of track and points now, I'd be hesitant to to buy into a G-scale track-power railway of any significant size.
( a range of cheaper possibilities come to mind, but I do have an odd mind.)