Are you prevented from running locos that are too heavy or who have too large a turning circle ? I guess not as I've seen a 9F on the WLoS - assume that wasn't possible in reality?, but what happens if you run it on, say, Maedy ?
Turning circles yes, I tried to start a 9F at Paddington on a curve and it wouldn't move. Weight restrictions do not seem to apply in my experience. AFAIK in reality a 9F would be too heavy for the WLoS as was the Britannia class hence the Clan class which is a Britannia 'lite' used on weight restricted routes.
