Mo, as a caller and as a session player, surely you would have seen and heard a wide variety of instruments. I'd imagine you'd steer clear of winds if recorders gave you enough problems to consider changing and the only other clues you've given are ease of learning and lack of intrusion; there's no hint of whether you want to broaden the sessions you play in or develop melodically, tonally (with different registers or timbres) or harmonically for yourself as well as in the sessions.   Given you had some piano skills in the past, if there's no other keyboard player in the session, why not noodle around on one of those smaller electronic keyboards with the volume turned down so that your sounds are supporting what's going on? While not as inexpensive as some already mentioned, they're often not as expensive as others already mentioned and a good player can transform sessions in many different genres.

Cheers, Rowan