First of all, I apologize if this information is already available elsewhere in the forums. I tried to search for it (even through Google) and just couldn't find a satisfying answer.
So here's the thing. If you take good old Yoshi in your party to Spellhold, his betrayal will automatically free a spot in your party for Imoen, right? What about if you don't take him at all and your party already has six members?
I'm about to start Bodhi's gauntlet, which is the moment when Imoen becomes available to join the party. I kicked Jan out as he was just filling in for little sis, but there's no option to send him back to Athkatla or the boat, just to wait there. I was able to read in an old forum (pre-EE) that anyone you leave in the gauntlet is lost forever. Is that correct? Although Imoen is set to become my party's thief (and main mage, with Aerie as a backup), I really don't want to lose Jan either because I need him for my shoplifting runs (his pickpocket skill is so high right now he barely needs a PoMT to steal anything from merchants).
Oh, and there's a dialogue option just before you recruit Imoen where you tell her there's no room for her in the party and ask if she can get out on her own. Will she be available after I leave Spellhold, and therefore be possible to keep both Imoen and Jan?