I find Keyclone incredible easy to setup and has alot of awesome features. However the PiP swapping is very laggy and isn't something you want to do in PvP - the swap itself has to occur then another second for the resize to full.

Keyclones PiP can also sometimes freak out and not put windows in the right place - this can also get you killed in PvP and PvE.

One of the great things about KC though is the commands, if one of my clients crashes I can quickly reload it and then login to that client and get back to my AV with little issues.

I was using Innerspace for awhile before I quit multiboxing for 6-8 months and while it was a bitch to setup - once it was setup it was damn awesome. It looks like its advanced a great deal since then. I'll probably renew my subscription and look into building a setup for it again.

As for HNK and GCP I havn't tried them at all.