triple S are expensive and have limited colours…but they do a good job
CAS have more colours available and are significantly cheaper but you have to do some work when you get the frame back (i.e. face BB & headset, ream out bearing seats).
I’ve had two frames done at CAS – both pretty good jobs and cheap (45 quid for a candy blue full sus…30 quid for a white frame and rigid forks). 3 day turnaround with CAS. 7 day turnaround with triple S. I’ve used old BB shells and headset cups and sacrificial bottle cage bolts to protect threads / seats and its been ok. Just get a Dremel!
Overall, CAS are cheap and cheerful. Triple S more expensive but put a bit more work in (limited range of colours tho).