Slowhand, I think that if you are still using the JMW arm, that you are in safe territory with the Glider. If you can stretch a little, or get a deal, the Benz LO-4 is a better one.
Of course you know I like the Shelter, but cannot recommend it on that arm because of potential compliance mismatch. The Benz LO-4 is as close as you can come to the Shelter, in a cartridge around that price, that has a high enough compliance to be completely safe with the JMW arm. It is a very good cart. If you can't find a good deal on one, then the Glider is the next best bet. It wouldn't hurt to check out the Dynavectors either, since they are some very fine cartridges that would work well in that arm. Like a 17D2 Karat. Different kind of sound than the Benz, and would give you some choice between the European and Japanese sounds.