The issue was primarily due to the display drivers installed by both tools and View agent. Older tools (and agent) versions would always replace the drivers, potentially causing a mismatch with the rest of the View agent - which needed matching drivers for PCoIP sessions to work.
It hasn't seemed to affect PCoIP connections from what I can tell.
If that's the case, you should be fine to leave your VMs alone - if the upgrade had broken something you'd know about it. I _think_ that the version of tools included with ESXi 5.1 and onwards has had the installer fixed, but I don't have the specifics.