In your initial post, you mentioned that you are going to pre-aggregate data for the group's performance. Assuming that you calculated pre-aggregated values for the group, and they are not associated with individual performers (or, rather all group metrics should be associated with all employees) - then the basic Section Access functionality works just fine.
I'm not aware of another approach that would allow both comparing to the total (without pre-aggregating) and limiting security to each one's data.
That is one of the strategies I'm considering, but I'm not sure it's the best one. It means I have to maintain two different aggregation logic, one in QV expressions and one in the load statement.
The other possible strategy would be to set on on-open action that locks the list selector to the individual, but doesn't lock for managers. I'm not sure if this is possible or advisable. I'm sure it would be less secure, but I'm not too worried about the individual end users trying to hack the app.
Something like that is possible, there are also scenario's where you not reduce the actual data, but a data island. Then depending on who it is use a variable set analysis to reduce to the correct level. This affects all your expressions though. See also this e.g. this discussion
Thanks, for the link. That is exactly the same problem I have. I think the solution they found will work for me, but I'll have to sit on a it a bit longer before I know for sure. I'm still new to QlikView, and can't 100% visualize how to set it up.