Well unless it's suddenly changed in 6.16 then you're wrong. If I use /nick when disconnected it will only use the first 30 characters, and when connected you can see from the debug window that mIRC only ever sends the first 30 characters (mIRC actually ignores NICKLEN and sends everything up to 30 characters regardless of whether it's bigger or smaller).
Perhaps it could be called a bug, on the other hand there has to be a logical limit to nicks at some point, otherwise one day we'll come in here and find some guy asking why his 1024 character nick won't fit in. 30 seems like a decent limit (my nick is 15 chars and it's usually the longest in any channel I use).
