As Slacker said, Key-up and alias cannot be abused in a significant manner, alias doesn't do a thing (apart from gaining 2 secs) and +-binds only let you have many actions on 1 button instead of 2, ie if a player found something issuable with the +- binds, he could also do it with 1 more buttons and 1 more finger.
What probably gives the biggest advantage is the non-blocking wait (/delay) as you could do a better pouncechomp script or a luci script that would never let a shot explode in your face (10-ammo shots ftw!)
About the cit timer, on servers running up to date qvms, the ckit timer also goes down when you hold the blaster.