For the straight skinny on how various 123A cells stack up, go no farther than this post on CPF (look at the higher amp rate charts for this application).

The SF batteries are good performers. There have been reports of some SF batteries DOA and some people avoid them as a result. Personally, I've purchased a lot of the SF batteries with no issues. However, to be on the safe side, I have switched to the Streamlight batteries which have top notch performance and no existing reports of problems. However, they are more expensive. I buy mine through brightguy.com. Many people like the batterystation.com batteries which are ok performers and cheap.

In the end, check out the graphs and avoid the really bad performers (see the Marathon and Golston) and buy in bulk over the internet and you pretty much can't go wrong.

-john