I'm not just against mIRC supporting this, I'm against it's usage on IRC as a whole. Of course whether mIRC supports it is a very significant indication as to whether it will remain in IRC (albeit on only a few servers) for another 5 years until the subject comes up again or whether it dies out much sooner. My reason for being against it is that it's needless, totally a case of freedom for the sake of freedom, no common sense in it whatsoever. As I have already said a channel name that long makes it much 'harder' to access and yet no-one has given an example what advantages using long names gives. If someone could simply suggest why such long names are necessary or preferable I could very well change that opinion - but no-one has. From that I can only conclude that there isn't one. The 'restriction' this places on IRC is virtually non-existent, does any channel anywhere use more than 90 characters in it's name? (Cue half a dozen people registering 100-character channels).
From a mIRC point-of-view also consider that a 200 character channel name would immediately take up more than a fifth of mIRC's maximum line length.
And yes, a maximum channel length of 50 sounds much more reasonable.