Hello,
My name is Dale and I will try to help you.
Generally speaking a shop that turns rotors is held to a mimimum thickness they can turn the rotors down. This with is clearly marked on each rotor by federal law. If they turned them down to the minimum and there is still a bit of scouring it usually will,not cause any problem. It could wear the brake pads a little bit fastert depending on how deep the scores are. but the alternative is to replace the rotor with a new one, which is usually quite expensive unless you buy the cheap foreign made rotors that are made of soft metal, Then the problem is that the soft rotors tend to wear about as fast as a good quality brake pads.
So those are really your options. As far a safety is concerned, as long as the rotors were not turned below the minimum they are just as safe a a brand new one.
Hope this helps. If you need more guidance, just let me know.
Sincerely,
Dale
Yes it would increase the surface area that the pad can apply but will not really make much difference unless there is a lot of scoring. The biggest reason that we turn rotors and/or drums is to get them straight so the pedal does not pulsate and to remove the glazing on the surface. The glazing will definately lessen the braking ability and increase squeal noise on new pads.
Hope this clarifies it a bit more for you.
Automotive Diagnostic Technician
40 years of Automotive Technical Knowledge, Teacher, Diagnostic Specialist