First of all i want to say thank you to autoprime for all the hard work and great information! Thanks!
Second, i wanted to add some information from my journey through sprint nexus programming land.
One question asked multiple times while i was reading though the thread is "how can i stop the phone from updating my profile!". If your on a sprint nexus, the system will update its data profile after a reset and revert all settings to the way they were on the sprint network. You can replicate this by going into Settings > About phone > Sprint system updates > Update profile. (This will reset your settings, so don't do it.)
Basically you need to freeze or remove the "Sprint system updates" app from the phone. I would only recommend doing this if your not on the sprint network anymore. I used Titanium Backup to freeze it, and it says the app is named SDM.apk and is located in the /system/app/ folder. With this app frozen or removed, you will not have the profile update issue anymore. FYI, Settings will crash if you attempt to open the Sprint system updates app after it's removal.
Also, if you are having 3G programming issues after following autoprime's guide, check your PRL files. This bit me in the tail like you wouldn't believe. I'm was using one of those PRL files that fix the roaming indicators on sprint phones and it turns out i was locked in at 1x because it was just not right for my phone or simply to old.
As a courtesy and a thank you, I'm attaching a modified (sprint roaming indicator fix) PRL that i've freshly pulled from my phone and modified with information from howardforums (Modified verizon PRLs for sprint ERI (roaming indicator FIX)). I can't post links, sorry. I'm using it on my nexus now and it works great, but be forewarned, i very well could have done something wrong in the file edit and you may roam without knowing it. USE AT YOUR OWN RISK AND COST. I'm also attaching the original unedited version as well. Both are from a verizon/pageplus flash.
53022.zip is original, 53022spt.zip is sprint roaming indicator fixed/modified.