It's all about movement. The company hired so many people this summer on the 175, so the guys hired at the beginning of the wave moved up the seniority list very quickly. They didn't hire much on the 145/CRJ though, that's why the reserve time dropped dramatically on the 175.

From what we hear in the company, they gonna hire 50/month, most of it on the 145, so now we are going to see more movement on that side. And believe me, they really need bodies on this fleet.
They also plan on hiring pilot for the crj, but the CRJ is a smaller fleet, so they probably gonna get 10-15 pilots per month for the CRJ.

Ultimately the CRJ is not gonna stay, so you can probably expect displacements in the future, the question is "when?" Probably not too soon, cause psa can't staff their planes.

For people living in Dfw, right now the 175 is probably a good option, BUT if they get the 40 more 175, it will probably come with a new base(s) (just my guess), meaning displacements.. and the most junior guys will be displaced.. it's all about timing. The 145 right now is probably the best bet.