If the Thompson Center was still being produced I would say get that, they are great rifles.
If you send a faulty T/C Classic back to Smith and Wesson, they will honour the life time warranty by replacing it with an S&W 15/22 which is nothing like a T/C classic. That's their preferred strategy, there is no guarantee they can repair your rifle because they rely heavily on cannabalised parts from other T/C classics or R55s that have been handed in on a warranty replacement.
You can get new magazines online and there are some springs available on the Numrich website.
What you can't get:
1) Firing pin
2) Extractor
3) Receiver screws
4) Various other components such as a the recoil guide plate and barrel studs
I've sourced some trigger group screws, trigger plate screws and barrel stud grub screws here in the UK but the receiver screws I ended up having them custom made.
So yes, the T/C semi-autos are good, in fact VERY good but you risk having a lot of headaches if something goes wrong or needs to be replaced.
I have two R55 Benchmarks here in the UK. I am slowly building up a collection of spares, but it is a much more expensive proposition than if I had two Ruger Target rifles.
Here's one of my R55s: