Heres my 2X4. Its a old kit(maybe 15-16yo) I made it to slope off the earthen dams around here in lite lift. I replaced all the light ply fuse parts with balsa and extended the nose 1 inch (should have been farther) so wouldnt have to add lead. I use a Gws 300 with the "D" gear, the slow stick motor. Its on a power pod and run it with 3s Li-ion cells propped down to draw about 8 amps. It climbs at I guess you would call a leisurely rate but gets there. I have a 400 with a D gear on another plane and should try it sometime. Weight is 29 ounces ready to fly includeing battery and everthing. I think a 400 would work good esp. with a nose mount. Maybe the 3 to 1 ratio with a 10X47 prop. Folder would be a plus. I also use the 400xt Hobbby Lobby brushless on other planes and it would be a good cheap choice also. Build it as light as you can and its a pretty decent little sailplane and thermals really quite well but it is really an excellent light lift sloper or tree line rider. With 2500ma batteries I can fly for 45 to 60 minutes hunting bubbles and still come down with power to spare

Good Luck
Bob