"I would be pretty surprised if any networks actually use this kind of a heuristic to ban clients. Certainly there are many legitimate clients out there with no such a timer, are they being banned? "
I know for a fact that many networks use it as a part of their protection, small and large, they do not get banned solely based on that result of course.But until now, all legitimate versions of mirc would never reply to 2 version replies from the security bots within 10 sec, with the standard mirc version reply.
There is a lot of bad bots that pretend to be mirc clients, that will reply with "mIRC vX.XX Khaled Mardam-Bey" but they do not have the hardcoded limit, so its an easy way to spot them, and do more checks.
This include ddos bots, hacked xdcc boxes and other malicious clients that shouldn't be allowed on irc. And such an easy way of spotting suspicious clients and watch them closer shouldn't be removed.
In my opinion, the limit to the version reply should be put back.
Why "fix" something that wasn't broken and something that people has started to rely on.
Anyways, keep up the good work.