There are two ways to do the same thing. Using the Personalize snippet:
[[!Personalize? &yesChunk=`yesChunk` &noChunk=`noChunk` &allowedGroups=`Group`]]
Using an Output Modifier:
Pros, cons, any thoughts?
The first con I can see to the Output Modifier method is that you can only check for one group at a time. If there are multiple groups involved, then you'd be better off using the Personalize snippet. Output Modifiers do have an "or" clause, but using it would quickly become more trouble than it's worth.