It is very tempting to ask you to give us their names... ;-)
But we all learn from mistakes. PwC in Germany and Switzerland also tried it based on ppt. file success for a while but have distanced them selves from it (except for PwC from North Carolina in the US who are not open to new ideas which are actually old facts).
I heard that there will also be some recommendations from SAP and TechEd "do's and don'ts" presentations with statistics from fails this year.
But if you think about it a bit then it is actually clear - you cannot split the start and myriad of cross-component and activities and org.levels from another. And how many times the user has the access does not matter much....
--> so pull it from the entry point as much as you can and you have more robust job roles and where-used-lists for the 7k application objects if you want to change something. It works fine. You can upgrade in 1 day. You can make mass changes via SU24 proposals and simulate the affect on roles. You can do a lot of funky things which are very scalable and reusable, also in the long run.
Cheers,
Julius