Does "b" or as you say "known about and pushed to the bottom of Sprint's 'to do' list", given that Sprint is on the record claiming they discovered a couple of days ago, make you feel more or less confident?
Neither. I think you hit the nail on the head -- a crushing shortage of the Evo, pressure at all levels to release the phone at the earliest possible date, and the reality that whenever something gets pushed too hard, fundamental things occasionally fall through the cracks. I can guarantee Sprint tested the phone's 4G performance quite well. It wouldn't surprise me in the least if I were to discover that the Epic is completely incapable of circuit-switched CDMA, and has serious problems moving back and forth between 1xRTT and EVDO. For one thing, "marginal condition" tests are really hard to pull off under real-world conditions. You can simulate edge cases in a lab, but you'll never replicate the kind of conditions that exist in real life.
Sprint isn't NASA. They have official procedures... and like everywhere else, when it comes down to a hard deadline with hopeless mandates and impossible goals that simply aren't going to be met in time, things get triaged at the last minute, skimmed over, and/or temporarily kicked to the curb. That's reality. It doesn't mean those same procedures won't be used to scapegoat someone, but it's the truth. When it comes down to a vast, secret conspiracy to massively throttle uploads, vs "ohshitwefsckedup", it almost always comes down to "oops".
I majored in both engineering and public relations, so I have a fairly good bit of insight into both. PR, Marketing, and Management come screaming and make impossible demands... engineering & development tells them they're crazy, gives them the real timetable, then finally gets beaten up into saying, "ok, fine, you win, now leave us alone so we can get back to work". PR, Marketing, and Management leave, happy and confident that it's going to get done... engineering and development sighs, knowing that it's not going to happen without divine intervention.
IMHO, the only real screw-up here (given the reality that they DID have to release the Epic ASAP) was that Sprint didn't have someone already monitoring forums like this, press release already written, acknowledging the upload issue and announcing a retroactive credit in the neighborhood of $10-25/month, prorated from the purchase date to the date the problem is officially solved. Instantly, the whole issue would have been defused. Some people would still gripe, but most owners would just sigh and forget about it.
Notice how once Apple announced the free skins, 99.9% of the bad press not coming from comedians and fanboys went away? They defused it. When Apple tried to deny there was a problem, they looked like complete tools (at best), and the poster child for Evil Corporate America at worst. After saying, "Yeah, we screwed up. Here's a band-aid, and you can get a refund if you're really not happy", their opponents had nothing left to really attack them with. Someday, that will be the first case study in every PR textbook in America.