Good timing, low hours.
My advice:
Make the jump if your family can survive the pay cut ONLY and ONLY IF you can get a reserve job. The reserve job probably isn't going to afford you a big paycheck with the recent cut backs and the most certain future cut backs. But if you can fly your tail off, you can solve your low flying hours in a year or two.
Momma and the kids are going to hate you if you do the regional only gig and you're gone from home 20-something days a month and barely making enough money to feed and keep the lights on. If you do it, live near your pilot domicile. That way you'll see them more often.
If at all possible, DO NOT spend the VSP money. Bank it. Let it grow. If you stay in the reserves to get a retirement, you'll have to pay it back. But if you invest it and allow it to grow, you will make something off of it. If you plan on using it to survive, you are taking a big chance that in a year from now, you'll be out of money and working for a regional in a much worse financial situation. Also, any number of political and financial issues can cause the pilot hiring to stop temporarily for a year which would be devastating for you stuck at a regional.
Your flying time is low; however, as a FAIP you should have a lot of Instructor time which is a bonus .. UNLESS it is in the T-6 which isn't as desirable. Airlines much prefer multi-engine over single-engine.
Delta doesn't have a PIC requirement. You meet the mins. But I suspect Delta is hiring only those with a lot of experience. You need to find out exactly who is getting hired by who and with what hours. I know friends with double the flying time and experience who have not been called.
Can you get a reserve job at the training command? Continuing to build PIC time / instructor time would be very beneficial.
Stupid question ... what is the timing of the VSP and the potential RIF? Let's assume you stay, how long do you think it would be before you were RIFd? When I went through the VSP fiasco, the VSPers had well up to a year to stay after their VSP award. The RIF never came for my year group. So potentially, you could have a full year or more before you were let go. Depending on what you're flying, a year or two more experience is valuable in your case.
I hope my random thoughts help. I made the jump back in '07 and I haven't looked back. It was scary. But, I didn't have a family to take care of. Good luck.