Sir i have been maintaining my cars, Mehran ->Cultus->Mehran Euro2 (& now Liana) all from Suzuki 3S, Plus i am also maintaining our Aspire from Honda 3S & i would beg to differ from you. If you know well enough your car & do not sleep over at 3S there is nothing wrong in going to them rather a road side mechanic. You just need to keep your eyes open.
I second you on doing minute jobs yourself but for me i don't have the liberty of tools & time that you have, so i cant afford it
Plus i dont always go to 3S , i get those jobs done from them which they are best at, For others (A.C , BALANCING & ALIGNMENT etc)i have separate USTAADS