RE: Height difference with change to CM-6 plug??
+/- 1/8" per side, yes. I didn't bother with exact numbers due to various plug and cap heights, personal habits when setting a plug cap, thread adaptors, etc.
Using the right type of plug cap and even more height reduction can be obtained but the Chinese don't make those types of caps. Only place you can get them now is through Valley View RC by special order.