Actually UKTS is useless unless you pay. I tried few times to download some addons from their site but I simply refuse to pay a middleman for others people work.
I hope Steam Workshop will work out well. It's big thing.
Understand your opioin, But the fee goes towards supporting the servers and everything else though. A lot of other sites out there of course to use for Railworks content.
I Love UKTS and have quite a few scenarios uploaded there as well.
Steam Workshop feature i am truely looking forward to as another method of sharing all content which gives it more of a public eye.

My own test route.

From Edinburgh & Glasgow

From Edinburgh & Glasgow

London to Brighton

Scenario im working on for The Mayflower Lines.
Click for bigger screens.
Chris