Looking at this from the opposite end…..
Weight is not the issue….. ! ! !
The handling method is…..
I hear of the traction engine people saying that a 4″ scale engine is much easier than a 2″ scale engine. One is tempted to LIFT the 2″ scale, but the 4″ just gets rolled into the trailer… No lifting required.
One does need to think about the handling though. I have a small folding 2 ton mechanics engine hoist, that is my workshop third hand. Makes fitting / removing a 40″ long 9″ barrel copper boiler a doddle. Accurate control and no issues. It would be a VERY HARD and precarious 2 man lift otherwise.
For 5″ gauge a rotisserie frame is the way to go when building, then a wee hoist. Once completed, a wheeled trolley and a storage track work well, roll off storage track, onto trolley, then into car boot or onto small trailer….
So the size / weight of an engine is not about the ‘lifting’ but about the provision of the appropriate handling tools. So if you don’t have room for or want the handling kit, then go small and light… otherwise set it up correctly and it’s easy….
All the best 🙂