What I would like to see is one you reach the limit, that's it. You can't set anymore. If you want to set more, you first have to disarm existing ones. This would help overcome the newbie problem as you could disarm the newbies mines and set your own (and the newbie would give up not being able to set any more mines which would enforce into their pea size brain there is a limit).

Also, I agree that timed and trigger C4 shouldn't be counted in the 30 count limit. Maybe have like a separate 10 limit for them (5 for remote, 5 for triggered).