After installing lots of replacement bridges, mostly on 70's/80's imports of one stripe or another, I've come to the conclusion that it's really OK to use miniature machine screws (4-40 or whatever's handy) as almost fail-safe insurance against the bridge coming off again.
OK, so that's my opener. Now, to backtrack, I would NOT use them on Martins, Gibsons, maybe Guilds... anything vintage... or anything where the customer didn't want them installed, but I'll try my damndest to sell it.
In the real world of repair (or, at least, in MY real world) most bridge removals leave a less-than-perfect gluing surface. On something vintage, it's worth the effort to re-glue tiny slivers and all the other heroics that the stature of the instrument calls-for. What I'm referring-to are the hordes of Yamahas, Arias, and the infamous "no-names" that we all see come across the bench. And half of them already came with the machine screws in the first place, so there's nothing new here.
And they can be installed in a classy manner, right? Countersunk heads covered with discrete MOP dots, or maybe wood inserts to match the bridge, etc. Whatever the customer's comfy-with.
I guess this "heartfelt confession" is meant to stimulate a discussion on the ethics of the procedure. Anyone else indulge in this guilty little secret? Mea culpa.