I own both a EAR834P (standard model modified with upgraded parts) and a Cinemag based SUT. I don't currently own a Shelter but have used both products with a Koetsu RSP and Benz Ebony. I prefer the EAR over the Cinemag in my system. Unless the Cinemag is a better technical fit for your cartride I don't necessarily think the move will be an upgrade. Of all the SUT's I've listened to, my current favorite in my system is the Hashimoto based SUT from Choir Audio. Not sure how it would match up with the Shelter but it's something you may want to check into. John at Choir Audio (very nice guy) produces SUT's with both Cinemag and Hashimoto transformers so you can ask him about specific recommendations with the Shelter.
Add Bob Devices CineMag SUT to EAR834P Deluxe
I have a chome EAR 834P Deluxe, which already includes an MC option. However, this CineMag has received great reviews. Using the EAR 834P in MM mode, in conjunction with a CineMag might be a worthwhile upgrade? What do folks think? I have a Shelter 501 MC cartridge.