There's an intriguing piece of film footage from the Lippisch archives of a P13a gliding in for a landing in a hilly region of German occupied territory in 1944 or 45.

http://www.youtube.com/watch?v=MvtxjSrImHw

Although the DM1 apparently never flew, at the very least a large glider mockup of the P13a did fly as this video obviously demonstrates.
Notably, the P13a in the old film sports the ramjet intake nozzle and seems to sport the walter rocket exhaust nozzle at the base of the tail. It has the forward landing bulge skid under the nose and many of the production features not integrated in the DM1.