I am not familiar with the term combat edge mask...I use a mask that looks like this
http://www.check6aviation.com/pages/...age/oxm121.htm the portion you have to push on to close your nose does make it somewhat tougher to do (valsalva). However, I would think it would be ok for you to take the mask down for a few seconds every time you need to valsalva. I would hope an instructor would not have a problem with that. If I come down from FL280 (cabin altitude around 12k or so) I usually have to valsalva 3-4 times prior to landing. I have always had to do this....in an airliner its about the same...