I have experience with both the 7S26 and 4R15 movements as I've owned many a SKX007J, SKX007K and the latest SRP043. In my opinion both movements are very reliable. I have found the power reserve longer on the 4R15 at 58 hours and 20 minutes (on average as I tested it three times) and it does run more stable, accuracy wise over a 24 hour period. My SRP runs well within chronometer ratings.
Dave
Dave
