Ki5 helped me recover from AeroPro induced tennis elbow as well. Currently playing with a Ki15 for doubles...love the quickness. Took a while to get my 1HBH dialed in with it but lately enjoying it. Can play it with full poly which I don't do with any other racquet.
Still prefer my old Fischer Mag Tour for singles though...just more accurate with it. The Ki5, besides the arm benefits, is a nice general all-around racquet. Not too heavy or light in any spec and quite spinny on ground strokes. I volley better with the Fischer though, and as mentioned vs. the Ki15, I just get more control from the Fischer vs. the Ki5 as well. Pure baseline rallying I might go with the Ki5 more often, especially if my opponent was the type that didn't come to the net so accurate passing shots weren't so critical. The Fischer is a little heavier static but lower swingweight.
Anyway, my next demo round, whenever that is, will have a least 2 PKs in it that I haven't had a chance to try yet so that's my endorsement. They are worth a try.