I spent time with the regionals and was a guard member then later Air Force reserve (both flying positions). My company never had problems with the military requests, however each mil flying unit seems to have a different personality. By that I mean you may find one unit requiring a lot more mandatory type "attendance" events were another may let reschedule to better times for you. And, unfortunately, a change of command can have a large effect of these things also.
I enjoyed the military flying - it was fun to look forward to some different flying for a few days, but there were times where balancing the two was a real pain. However, it's a great insurance plan for the day your airline merges, closes, furloughs, etc.
Seemed to me the guys who were best at it were the ones who were located physically close to the unit - they could go out and spend the afternoon and it didn't require major planning to do.
Hope this helps.