We live in a quick fix society. Developing technique and talent takes way too much time and getting good instruction can cost a lot of money. For example, buying an APDGT is a much quicker fix for getting more spin and power than developing good technique that produces spin and power with any racquet.
OP, Why not use this time to do a serious demo of racquets and maybe you'll find that none of the racquets you already have are really what you need. For example, the ProKennex Ki5 is everything the Pure Drive should be. If you have been playing for some time now, maybe you could try the Wilson 95's. They are a little more heavy but play very well. On the lighter side is the Bab Pure Storm Tour, which hits with all the spin and power of a Pure Drive but with more control and much better feel.
My point, is, rather than ping pong between the Pure Drives and your old racquet, maybe there is a new soulmate just begging to be discovered that avoids a long period of ping pong and irregular results.
Lastly, I am a big proponent of the "It's not the arrow, it's the Indian" argument. I thoroughly recommend getting professional training every now and then, if not regularly, as this tends to make differences between racquets fairly small and good results can happen with just about any racquet. And the magic really occurs when you have good instruction and your perfect soulmate.