I have disputed with CSC and have called them once. Seems like they are impossible to get a hold of on the phone and the CSR I spoke with was semi-OK to deal with. I can tell you that I have had good success disputing with them.
You mentioned your EQ is 632, and I've noticed several people who say they have been approved through NFCU with scores similar to that, with limits in the $3K-$7,500 range, but those are just postings in various forums around the web.
I'd be interested to know what is driving their decisions on CL's, as I applied on the phone, didn't ask for a CL, I was just told, "Congrats, you are approved for $17.5K @ 11.9%". My income is pretty good (~ $100K), but of course my score (650) and the derogs on my report couldn't have been a huge help, but who knows.
Anyone else want to chime in on their approval experience with NFCU, your CL, scores and income (if you're OK with that). Maybe we can find some patterns in approvals and CL's.