True... But is following what Blue said fine? "Weight over 320g, SW over 320, balance over 4 HL, RA below 65."
I feel like if I eliminate the Racquet + strings then I know it's a problem with my technique. Just trying eliminate anything I can at this point.
I think you're doing the right thing by searching for a softer rig, since you're already using a decent soft multifiber in your Pure Drive and still not comfortable with it.
The racquet search will take a little time, so be ready for a couple of ups and downs. Even if you demo a racquet that's better for you, it's also entirely possible that the sampling sessions will give you a little soreness just because you're using unfamiliar racquets. Whenever we try new frames, it's typically the case that we'll rack up a few extra mis-hits while making adjustments. The frame may be ultimately more comfortable in the long run, but the getting-used-to-it process can be a little irritating.
Even a racquet with an arm-friendly reputation can be significantly harder on the wrist and elbow when strung with a poly or poly hybrid. If you need more comfort with any new racquet, I strongly recommend sticking with synthetic gut or multifiber to help stack the odds of success more in your favor.
What Blue said is fine, but we all have our own best fit. Even if the specs of a certain racquet are right in general terms, you'll probably recognize your better setups when you have a good hit on the courts. You may benefit from keeping notes on your demos. I've personally always enjoyed a heavier racquet, but I also have a better time with handling that extra weight when I have more HL balance. One model I routinely use weighs 12.8 oz. and balances at 10 pts. HL. The greater heft is more stable through the ball and the HL balance gives me better maneuvering, especially around the net. My setup isn't for everybody, but lots of players prefer more HL balance when playing a heavier frame - something to be aware of when demoing.
If you can eventually get a test drive with the DR 98, that might be a good one. That Prince Tour Pro 100 ought to be a nice soft hitter - I have an ESP version of that racquet among my loaners and it's very cozy. Since I'm a big Volkl nerd, I'll also recommend a look at their options. The Super G 10 295g and 325g might have something to offer in terms of comfort and performance, plus they're marked down.