Stop answering 9E issues when you are at VX. "Dual qual" was more than a -200/900 differences issue (we had a 3-day course to transition on the unfenced 9E certificate). The problem was "a few fold". As you mentioned, pay, is still an issue (as an loa on the original JCBA introduced dual qual), but also currency (hard to stay current, and no point when the A/C only goes through one base that is closing),the FSDO (FAA) allowing it, followed by it being impossible to remain current with the current fences. Most will argue "safety" until the pay goes up, but with basically 3 groups right now (-200, -900 fenced, -900 unfenced) the training/pairing construction/pay issues become a big problem.

In time the "current plan" is entirely a -900 fleet. That seems to bounce around a bit on the timeline, but "dual qual" with a continuing training bubble makes zero sense. Yea, the -900 has fixed issues that the -200 has, performs better, but handles much differently on T/O and landing. Unless -200's will remain (in the same domiciles as -900's) on the same POM/FOM for a good while, dual qual training and contract amendments are pointless. It's more training and qualification events, plus added pairing restrictions. The end result is more days working for the same paycheck. Other carriers (Mesa/PSA/skywest) structured training and manuals to fly the multiple derivatives within the same hub structure. In the current and future state of 9E, it's not feasible and not cost effective.