I've just replied to this in support.
For future reference, Pluggo 3.5.4 will require the CFM extensions to
work in MaxMSP 4.6. However, installing the CFM extensions will not
break Pluggo in other hosts. Once we release Pluggo UB this will not be
an issue. If you are on PPC, you can still use MaxMSP 4.5.7 with no issue.