Definitely. The reason many people do not go for 21mm is the prospect of having to build lots and lots of track. Of course many do, and to an excellent standard, but I couldn't possibly imagine going to 21mm gauge,
As layout no.2 would be a large layout, and a pain in the ass to build all the track. Modelling the 1950s means that the bulk of my locos would be kit built and therefore 21mm compatible. If the fast track was there, I would seriously consider, going to 21mm..
Just my ramblings..