I have 2 different sets. a Comtek unit which my grandparents bought for me when I was still in elementary school... still useable but the receiver is a bit busted up (my recliner tried to eat it one night!). Just don't like using the neckloop though. It's kind of finicky these days as well, I get a lot of static-type of sound which is quite annoying.
Also have an old Phonak transmitter (the HandyMic) which doesn't even hold a charge. Have an MLx receiver which I got with my last hearing aid. I tried using the HandyMic when I was still in school (9th grade) and didn't much care for it in classroom use; so it was mostly used to listen to music with.
Am working with Vocational Rehab on acquiring a Phonak Inspirio transmitter and a ML10x receiver for my Naida hearing aid to use when I go to college next semester, and I'll use the MLx I already have with my Neptune processor.