What a coincidence, I have just decided to modernize an S12-S with an RSX group, and thought I might look at dual pivot calipers too... I had pretty much decided to avoid the cost of new dual pivots since I have some decent caliper brakes in the parts bin... But, do I go through the effort of drilling. I don't mind drilling the front, but I haven't checked the rear bridgs to see how well it could be drilled.

I also briefly thought of moving to center-pulls, and decided that I didn't want the cable routing necessary for center pulls... unless I ran across a road stem drilled to be used as a cable hanger for center-pulls/cantilevers, like I have seen for a couple of vintage mountain bikes...

All that to say, I am responding to see what others think on the subject.

EDIT: Mine is possibly complicated a bit by moving from 27" to 700c, and I haven't measured the reach yet.