Depends. I once put an eggdrop running TCL beside a mIRC bot with kick scripts and flood scripts, listening for an identical event. The mIRC bot crapped all over the eggdrop for swearkicks because mIRC deals with colour/bold code avoidance of swear detection far better. The mIRC bot was in his jammies and on his knees saying his nightly prayers even before the eggdrop got to the middle of "ahhh he swore". The eggdrop handled flood/repeat kicking better though but it's performance didn't shine through until I did a mass-flood with a few clones.
Overall I believe that the reason why mIRC bots arn't convenient is due to the lack of availablilty of affordable hosting for them. In my view, if you run a Windows box 24/7 which hosts a mIRC bot guarding a room of less than 500 users then a mIRC bot is perfectly adequate. There's no real need to pay for a shell account simply because something might be better yet not give any real performance boost based on one's circumstances. An eggdrop would only be better if the load required the difference in performance to be better.
