I just started. Series FX loop with chorus, phaser, flanger, delay, reverb, tremolo. So far so good, but I've got a lot of playing and experimenting to do before I'm sure it's going to stay that way a while.
Just a head's up, most analog pedals don't like line level signals, Boss "single" digital pedals don't either. It won't break them, they will just distort in a bad way.
I haven't done this with my Mesa amps. I have my delays and a Boss PS-6 Harmonizer in the loop, but leave the phaser and chorus at the end of my input chain. I do have control over the FX send and return levels with the amps.
Thinking about adding a BBE Tremor and a Soul Vibe to my board; these will probably go in my loop. That will give me some additional versatility.
Yeah, it really comes down to whether the pedals play nice with the input impedance of the loop. I've tried various experiments but ultimately came back to everything into the front of the amp, which I set as a clean-ish platform. IIRC TC Electronic Flashback (and maybe others) self-adjust for input levels.