So, I've been reading a lot and it seems like a lot of people are against the dpa for a 4.5" lift. I've already installed mine, not really wanting to take it all apart again, but looking at the drag link versus the track bar, I might have to...any input?

Never droo pitman alone without also dropping track at frame or raising at the axle

The PO installed one on a lifted Jeep I bought and I couldn't keep it in my lane on the road and it had bump-steer.. I removed it asap.

In theory you shouldn't drop the pitman arm without a corresponding change in the track bar, as has been stated above. The question now is, is the change too much? If you are not experiencing any death wobble problems then you should be OK with that. It is not enough of a change to worry about unless you have other issues which would contribute to death wobble.