A quick story of my own in regards to scale and curves dilemma on my layout. My layout is 3 loops, inner is 036, and the two outer loops are 048. It's all I could fit on my table!! I desperately wanted scale GS Northern Class 4-8-4 on my layout, both SP and WP. I have a K-Line by Lionel semi-scale GS-4 Daylight from 2009, and it's a nice model, but wanted the more realistic scale size. All the Lionel GS series say they require 054 curves, but I wasn't convinced of that. So I asked a friend that has a Vision Line GS-4 if he could run his on some O48 curves. Argh, he didn't have any O48 so I had to ship enough O48 sections to make circle to him. No biggy, just time consuming as he's in Kansas and I'm CA. He got the track, put some power to it and ran the Lionel Vision Line GS-4 around and around until he was satisfied there were no issues. Woohoo, man I'm looking for a GS Daylight Scale ASAP and found a NEW Lionel Legacy GS-2 from 2012 catalog. It runs great on my layout, I'm a happy camper. Then, after that I had been looking for a WP GS-66-77 for over a year, and one popped up on eBay for a great price. Said it was used, but if it was I couldn't tell, even the box looked new. However, it is from the 2004 catalog, so it's TMCC and not TMCCII (Legacy). It does have RailSounds 5.0 with dual speakers, sounds fantastic. It runs great, I'm totally happy with it. I'm working on a video of these GS Series, but taking longer than I had anticipated. I'll post it when I finish it. These have a little overhang but they look pretty darn good going around O48, check out the photos.
Note, all the switches on the two outer loops are O72 and not O48. I did test O48 switches with the GS's, and no issue there either. I just like the smoothness of O72 switches and they're the same length as O48.
These are my favorite steam locomotives!!! I'm beside myself they work on O48. I like the subtle differences between the SP and WP versions, like the number board position.
