This type is easier on servo's as both the servo's are in the usual fixed position, but it may take a bit of experimentation to get the throws you want. You can make the levers from paxolin, fibreglass printed circuit board, large servo horns or similar. Make sure everything is as slop free as you can get it and it'll work well.

The sliding tray type works very well but demands you make sure the tray slides easily on its runners otherwise undue stress is placed on the pitch servo which has a hard time anyway because it has to move the whole roll servo in its tray as well as the elevons or whatever. Also in a crash the weight of the tray and roll servo suddenly shooting forwards will break the pitch servo arm or even strip the servo gears.  G :-)