Welcome back, @dBerriff.
I'm new to the hobby, just six months in, and, like you, the TT:120 scale appealed due to space constraints. I'm HM7000 only as I have no experience with DCC.
My experience has been mixed. My Blink Bonny worked for 10 seconds and had to be returned due to a faulty decoder. The warped track needed adjustment. The Pullman coaches drag, as does the Mobil tanker. The HST cars don't couple properly. I'm waiting for my Flying Scotsmen to be repaired and returned.
There was a point where I considered returning the lot and try something different.
But...
I've built my first baseboard - my first attempt ever at woodworking.
I've now acquired boxes of tools and other modelling bits (which is essential for every railway modeller apparently).
The Class 08, modified by This Way Works with the sound chip and stay-alive is a delight!
Hornby's customer and technical support teams are exemplary and as others have pointed out, Hornby are refining their models based on feedback.
The Hornby forum members are a great bunch - very helpful and informative.
I really enjoy playing running my layout as it grows. Well, apart from the fact it isn't big enough, so I'll have to build another one .
So I'm sticking with TT:120 as I think it has a great future.
Martin