In reply to verificator:
This is a very hard question to answer without more specific details about what the feature difference mean for the testbench. Can the classes easily be extended from the base class, or will you wind up overriding methods and copying/pasting code from the base clsss methods into the overriden class methods?
If there’s ever a case when there are two instances of the IP needing the different sets of features in the same testbench, then class extension is the only way to go. Macros cannot target specific instances.