Records are just a function of time. Stones are not better in my opinion but in the hands of a skilled guy (and with good stones and tight non-tapered pilots) they can come close to matching the Serdi stuff - they just take a lot more time to get there. Some believe the stone can get a finer finish for the actual seat angle and use cutters to cut and then stone to finish the seat angle. Using worn or cheap stones, or any type of tapered pilot is a lost cause even if God himself was doing them. The TCM-25 I have is decades old, uses cutters, and it could do a near-perfect seat. It's much more about the operator than the equipment - to a point.