I have no idea why they changed to be honest. The electronics never fail in the S1 relay. The issue is that there is 1 terminal on it's own on the end and this gets a bit of a kicking from the drivers foot being over the throttle. Because of the flexing, the soldered joints crack and break. A quick soldering job and it's repaired. This may be why they changed to the pink relay, which also burn out but that is usually a printed circuit track (which again, can be fixed with a soldering iron).

The S1 relay has an inbuilt adjustable rev limiter, which is where the rev limit comes into play.

I occasionally offer to fix some of the fuel pump relays for the price of a courier to return the relay but nobody seems interested for some reason.