It's a valid point, as there's a tradeoff between capacity and durability. SureFire seemed to have chosen durability, which makes sense as the Peacekeeper is designed for patrol duty.
Do we even know what brand of 18650, SF is using in their 2600mAh 18650 cells?
Could be Chinese dreck, could be a nice Sanyo, who knows?
The big five: Sanyo, Sony Samsung, LG and Panasonic all make quality cells in the 18650 size.
Durability of the above offerings will be mostly predicated on how a person treats them, rather than any inherent capability of one over the other.
Obviously, all bets are off regarding the Chinese stuff, even though some good Chinese cells are coming to market--like many of the newer IMR cells.
You can have capacity and durability, but the bigger issue is how well suited that cell is to handle the 'current/load' of any particular emitter.
I don't think that the relatively anemic P1R will greatly tax a cell and if the P1R hits 3.0A I'd be surprised, so any of the ICR cobalt chemistry cells should be sufficient. If you start going above and beyond 5.0A then maybe an IMR, or a hybrid would be best, however, these higher current handling cells have slightly lower capacities than the light duty cells.
How you charge, discharge and store your cells will matter quite a bit if you're trying to eek out a lot of cycles.
Personally, I wouldn't buy the SF branded 18650s, as I'd prefer to look elsewhere and know what I'm getting. Also, I'd save a bunch of money in the process, but I understand why people want to stay with the SF marque.
Chris
