I have a 457 plan... not sure if you can roll anything INTO it, I know you can't roll a 403b into it. I know you can roll the 457 into a TIRA, but that's dumb.
Couple thoughts:
1) If you COULD roll that money over, it's already been taxed, but then when you withdrawal it from the 457, it will be taxed again. Ouch!
2) You may not be able to roll over the Roth but you could withdrawal previous 5 year old contributions and live on those while you max out the 457. The advantage here is that you can live on taxed money while you defer new contributions to your 457. Cool! But it sounds like you don't have enough in the Roth to cover your expenses for 1 year while you defer to your 457.
I think your time line of 14 years means you should be contributing the max to your 457 while you have it and then contribute anything left over to a Traditional IRA, if you don't also have a 401k or 403b, cause you can have one of those along with a 457b at the same time. Your 457 account can be treated as your taxable account for now (no penalty but taxed), anything you put into your a 401k or TIRA can be used in a Conversion Ladder while you live on the 457 funds. My wife and I both have 403b's and 457b's, we max out each, this leaves us with very little to put into a taxable account, but thats ok, because when we pull the trigger, we have options: Live on the 457 funds while we do 5 year conversions, or live on part time income while we do conversions and leave the 457 alone until we don't want to work part time.
If you don't save anything into a taxable account, you should also have an emergency fund, since it would be very hard and expensive to pull any of your investments for emergencies.