Pay cut, seriously???
Are you guys for real, yeah sure some of the senior SO's who fly only overtime sectors are making a killing, but the 737 pay scale is nowhere near as bad as it was a decade ago, to the degree that in the last 12 months there would not have been much pay differential between a 737 and 330 FO.
I doubt if any 330 or 787 SO would come anywhere near a 737 FO, particularly now the company appears to be focusing efforts towards mainline and there's a good chance of a few bonuses being paid!
If the 747 and 380 route structure changes with the introduction of the 787 meaning less overtime, many SO's will be facing pay drops on those fleets also.
The real factor for most deciding on a move to the 737 will be their work ethic and if they want to work in a busy, intense environment for career their development.