I personally don't see a need to seperate out by size. If it is live steam it belongs in this forum as the technology is the same irrespective of size. If it is not steam powered it belongs in riding scale railroads.
I'm with Keith for two reasons.
First, as Keith says, steam is steam. We all share the same interests and issues with perhaps just a very few exceptions (the o.p. question about suppliers being one). A problem or question about anything steam is an opportunity to learn and contribute to the general knowledge.
Second, another subforum just makes it harder for cross-pollination of that knowledge. By talking to each other, ideas useful to one group could be useful to another. I visit a forum in another field of interest and there are so many subforums (61) that items of interest in one are missed by those who visit another. Cross-posting is just about universally frowned upon, so the post sits in some forgotten corner of the internet, not seen by others who might benefit or contribute. Some of the folks who post in the lesser-visited ones wonder why they aren't getting many responses.
(And more subforums just increases the duties of the mods, sorting out and moving misplaced posts.)
Greg Lewis, Prop.
Eyeball Engineering — Home of non-interchangeable parts.
Our motto: "That looks about right."
Celebrating 30 years of turning perfectly good metal into bits of useless scrap.