i agree that an experienced driver will do a better job without abs by keeping it on the point of locking up but... real world with wet sometimes greasy roads and some idiot drivers out there etc its always nice to have it there incase of emergencies.
Quite often instinct kicks in and its hard to not just slam on the brakes to avoid an incident thats deveolped just ahead without warning.
In those circumstances the abs would prevent a bump, depends how confident you are and how much driving experience you have, i have an advanced driving qualification (not IAM by the way) but i still like having abs in the background just incase, i guess the amount of road v track use as well is a factor.
ps also check legally that as your car was originally fitted with abs the act of disconnecting it and then being involved in an accident (i.e kid runs into road without warning) check you may not be liable for your vehicle causing an accident through disrepair.