How much are they asking ? A compression test is the real indicator of the overall condition of a diesel.... but specific things can be wrong or worn which do not show up on the compression test..... If they are asking a reasonable amount and it feels as good as you say it does it might not need any more PPI than you have given it ...
However, in general I always suggest taking a car for a PPI to a business which does NOT do repairs at all.... which leaves out your local indy you usually deal with....
Those people ( like Lemon Busters) ... have a check list and will check out the entire car.... which is a good deal in my opinion for what they charge... for typically $100..... a car can have a great engine and look really good.. but have something (for an example) like rust around the antisway bar mount which can take the luster off any MB fast....

How did you determine that the cams have no " flat spots' ?
How did you measure the ' blow' ?