New Tactician owner here...
I played legos the other night when it came in to see what my options were.
I tried to put my E2L clip onto the tactician body and it fit the slot, but not with enough tension to hold it in place. It wiggles around a lot and won't hold pocket tension because it can move toward the head. Oh well, no biggie.
My preference is for clicky tailcaps anyway, so I'm using the tactician head on the e2l body with a Keeppower 16650 for now.
I have a Nitecore RCR123 charging now to see what I can get out of a 1x123 MDC body and tactician head.
Also noteworthy (to me at least)- neither my KL4 nor 60/3 E2L head will turn on at all on the Tactician body.