Oh yeah, there is that setting, gonna have to try that as I'd resorted to using it as the master so all my devices had the same wonky accuracy as it. I thought it was the heat affecting my QY700 when I really noticed the mismatch of supposedly synced machines. I'm even thinking the Keystep's accuracy is far better than the BSP's....
This site has a list of MIDI timing jitter and latency for a huge number of devices. It does have the BSP tested, but it's an earlier firmware, which is reported to be a lot better accuracy than what you have observed. Maybe installing the older firmware might tighten things up? Just need to check what will be broken in that version as the trade-off for the better timing (edit: it's the 1st update, so a bit will be missing compared to now!)
I've been using a drum track to trigger the well hated Rhythm Wolf with great results (after turning off the noise injector they call Howl, compressing the drum output and using my own distortion
). Laying down a kick track running a Vermona Lancet Kick for simple rhythm, then sending the Wolf a trigger where I'd usually put a snare/clap, open hat/cymbal or woodblock/click to push it along and deliver me an event from a cue, more than merely syncing it and then changing sequence length and tempo division. And dare I turn up the bass on that thing, downtune the hell out, turn the res, envelope and cutoff to zero while turning the decay on full, it has an actually room shaking sub sound that abruptly ends after way after anything else. Program in some lost bassplayer notes on it and instant tripping dub reggae bassist trying to find the start of the round.
I'm thinking of trying out the same technique with the Volca Beats, just I'm starting make a spider's web across my room....
I've looked at Electro-Harmonix's multiclock gate thingy in the past and recently peeked at it again, thinking maybe the clk timing accuracy might be higher and also run those pesky Korg and TI machines independently, but really sacrificing three gates still leaves room for an average analogue kit while some pseudo random percussion happens in between the usual beats.