Took a look at the Nexon "careers" page

Vetting new people or vetting reports?

How long did it take an MWLBer to catch a hacker, as opposed to how much time did a GM have to spend on such a report until the ban?
If there had been 100 MWLB members patrolling at all times, would there have been enough GMs to handle their reports?

Both really. First vetting new people faster, and getting them brought up to speed faster. Having just a handful of GMs in charge of thousands of applications was going to be a slow process no matter how quickly they acted. So I'd have taken the first few MWLB, promoted a few of them into handling the newbies, while using the new hires to judge potential applicants since they'd know what qualities to look for in active members. Then, when the program got big enough, say around 100 people, take a few more of the older volunteers and hire them to help clear out the reports faster. I'd probably just set it up as contract work so they could get away with paying us crap, and have no benefits or whatever, but I suppose the whole DCing issue might be enough to put a stop to that. Though I guess you could give them a budget for decent internet access, kind of like how some commuters get a gas budget.

As for catching hackers, it varied. Some places had hackers on almost every channel, so a quick sweep would net you like 10 to 15 names. Other times, it'd be a struggle just finding 2-3 of them. It was a rather huge timesink because we had to collect evidence of every hacker we found, and upload it to youtube, when it finally was working that is. Occasionally you could get away with just screen shot evidence, but that was mainly the stupid botters in the FM and around Henesys. The ban time, well sometimes it was immediate, sometimes it took ages.

And as far having enough GMs to handle reports, well I doubt there would have been enough GMs to handle it all, but we only saw a small fraction of their team, so I could be wrong. I mean, just based on my own guesstimates, they probably had a team of 20-30 GMs, which was the only reason I can think of for how small the program remained.