I have played an Ecstasy 101b a few times, and currently own a 3534 since mid 2021. The 3534 is a lot like a stripped down 101b, but the red channel has more gain - others say it's closer to the XTC Classic in that regard. I really do like the 3534, but I've been on the fence of trading it for something else simply because of GAS.
Sounds great through V30s, sounds great through Greenbacks. Clean channel to my ears sounds much better than on the 101b.
Some people complain that theirs has a noisy FX loop. Mine has a slight amount of 'hiss', but it's not nearly loud enough for me to complain about really. If it ever does become an issue, I'll likely remove it and put in a zero-loss loop and call it a day.
Overall, it's a damn good sounding amp. Price wise, for a few/several hundred more you could probably get a 101b if you look hard enough.
What's the price on the one you're looking at?