Shrooms/Juggs should certainly be mezzable by a chanter without Rapture (Dazzle on under-55 shrooms, Glamour should at least land on everything). This camp is mentioned as a situation where Glamour of Kintaz, our near-useless level 54 mez that is like Rapture but resistable and capped lower, could be used. If you read the comments in the below link, you see that Jugg groups would use chanters as low as 54.
http://eqbeastiary.allakhazam.com/search.html?id=4570
(note that GoK had been changed to be a much better spell by this point The resist check, however, was unchanged and should land the same amount as described here.)
For shrooms, I remember reading that GoK could be used to crowd control 56+ shrooms and to interrupt their heals. I'll add the link if I can find it.
Edit: Found one source on Shroom MR at Monkly Business. The original post was during Kunark, even.
http://www.monkly-business.net/forum...ead.php?t=8750