Cyanogenmod 11 has been put out in the wild for the Nexus 5, while not a stable release, it is a M release which usually means a certain amount of stability. I tried the ROM and I must say all is really working well besides data. I tried flashing the 4.3 zip from here: https://help.ting.com/entries/23423026-Flashable-Zip-Fixed-LTE-eHRPD-for-CyanogenMod I only had 3G data (I have very strong LTE where I live). I also tried dialing *#*#DATA#*#* to check or change the mms link if necessary and that feature didn't work. It seems like some carrier specific things to Sprint aren't in the ROM yet. That was my experience so for would love to know if anyone has things working better if so maybe we can pass it on here.
EDIT: I have things working really well now. I was trying one of the flashable zips and really not having any luck with any of them, or inserting the apns directly in the ROM before flashing. I got the correct settings here: http://forum.xda-developers.com/showpost.php?p=46628324&postcount=9, so using the voice dialer, dial open apns, then edit both Sprint EHRPD internet and Sprint LTE internet, changing apn="n.ispsn" to apn="n.t8.ispsn". Also change the mms link in both of those to http://mms.plspictures.com and I think that should be all that is required.
I also know that starting with at least the 12-30 CM nightly that the *#*#DATA#*#* dialer code is back.