RE: Monokote Hinges
They won't blow off any more often than any of the monokote covering on the entire a/c blows off. There are lots of covering seams on a model that're against the airflow. And you can inspect how they're doing and if you see any coming up, just iron it back down.
BTW, don't worry about having already shaped the surfaces' leading edges. The unshaped gaps actually aren't the best mechanical setup for hinging except on very thin surfaces. What happens is that the axis for your surface winds up with two different locations. Instead of having one "joint" it winds up with two. When your surface is moved up for example, the surface hinges at the top. When it is moved down, it hinges at the bottom. Now, where is your control horn positioned? It winds up seeing one pivot point when it goes one direction, and a different pivot point when going the other. What happens isn't a big deal, but that system shows the servo different leverages and sometimes different lever-arm lengths depending on how wide the surface joint is and where the control horn is placed. Not a big deal, but not a good deal either. And it will give you some differential deflections, again according to how wide the top of the surface is from the connection to the horn and how wide the bottom surface is from that same connection. More of a big deal depending again on how wide that "now flat" joint is from top to bottom.