OK, I'll chime in:
http://www.the-answerman.com/sidlist/prl/index.asp
It's my archive of Alltel PRLs along with instructions on how to install them on a 6700.
Quick background:
The current "official" Alltel PRL for the 6700 is 30008. This PRL, as well as the previous "official" PRLs for the 6700, does not allow EvDO roaming on Sprint... 1X only. However, you can use 40007 or 40023 on your 6700, and either will allow you to roam on Sprint's EvDO network. 400xx PRLs are actually the PRLs used by the data cards, and have recently been pushed to some of the Alltel smartphones like the Moto Q and Treo 700WX, but not the 6700 for some reason (probably having to do with the 6700 being EOLed).
If you are always in a native Alltel EvDO area, these PRLs won't do you any good... but if you travel, or if your area is still 1X only, you might want to give them a try.