I used one 8411 on each elevon. I did not split the elevon. I've seen some guys put the rudder servos in the fuse( top or bottom). Pretty clean, but the rods will be much longer. I would use the voltz, but I already had the other ones.
Just get good quality servos for everything else, does not need to be big money. No reason to put a $100 servo in to actuate an air switch or brake valve.