The salt level tends to fall over the course of the season due to splash out, backwashing, and overflow. It is often simplest to adjust it to be at the high end of the range at the start of the season so that it ends the season within the low end of the range, without requiring any adjustment over the course of the season. If you don't mind observing and adjusting the level several times during the season you don't need to go that way.
Higher salt levels will increase the conductivity of the water which translate into longer cell life. This is why the recommended salt level for the Pool Pilot is 3000 ppm. BTW, the Pool Pilot will work in salt levels up to seawater strength but you don't want to go too high because corrosion then becomes a factor.
I understand your concern. I was just going by Pool Pilot's printed statement that optimum efficiency is generated at a level between 2500 and 3500. Hence I thought if that is in the optimum range why not? I suppose they would rather have me burn up cells faster than slewer. Perhaps you can tell me if there is any reference data on the corelation of salinity to cell life, or in just plain english how much less lifespan can I expect at say 2700ppm?
2700 comparing to...? 3000? not much at all. I doubt that you'll actually find such data as life expectancies are normally never tested in real life (apart from customer's pools). They are usually calculated based on accelerated tests in hard conditions.