Clint,

I fly my Akromaster with fixed flaps and an old Fox .15x with an 8×5 Rev-Up on .012" × 52' lines. It flys very well. Your Medallion .15 should do just fine, although you may find that you'll need to add nose weight, as the typical SIG supplied fuselage I've seen tends to be a bit heavy aft of the wing.

I might suggest that you provide for the possibility of making your flaps operable later, should you choose to do so. Mine is built that way and I may change the control set up this winter to permit the flaps to operate this winter. Since the flaps are already hinged, it will be a fairly simple task to accomplish. It was a simple matter to hinge the flaps in the building process and fix them until a later time.