I appreciate everyone's interest in this topic! All good questions, and yes I apologise for not mentioning that the rule would be run from an assembly.
Here's my workflow:
Lets say we have an assembly of several parts. Each of these parts will have one machining operation (a simple routed profile) performed on it at any given time, and I want to easily switch between these profiles (from the assembly file) to check fit etc. The profile to be used is specified using a parameter in the assembly. As there may be a dozen or so possible machining operations to choose from, they have all been created as features in the parts (with the profile for each machining being brought in as blocks in a derived master part), and I am looking for the simplest way to suppress ALL the other profile extrusions, and then simply make active the ONE profile specified by my parameter. Its a shame that you can't place features in folders to group them and control their suppression that way...
Harco this is brilliant stuff. I didn't twig that you could use the RMB properties on a feature for this (suppress feature if driving parameter ISN'T the right value. This is exactly what I need and perfect for switching a large number of profiles. Thanks to everyone for your help, the system works!