So, I am very far from being an expert on RC set up but I have a bit of experience in full scale race cars based on production cars. A lot of time and money is spent to have as little compliance in the suspension as possible while also making sure the suspension is free to move...ie. removing "sticktion".
I for one think shimming is important to get a car that is consistent and have done this on my old TA-03 and F201 as well as on the TT-02 that is being built currently. I just don't see how shimming can hurt the performance of a car as long as it is not causing binding in the suspension.
my $0.02
Cheers,
Jim