Which battery is better?

I was planning for a standby battery for my Canon EOS 30D. I saw Canon's BP-511A Lithium-Ion Battery (7.4v 1390mAh) priced at $49.95 at B&H and also Impact's BP-511A Lithium-Ion Battery (7.4v 1500mAh) priced about $15 less.
Has anyone used both & found differences in quality? Is the $15 price compromise not worth it?

Let me know
Gautham

I haven't used Impact's brand of battery, but I do use Delkin's e-film batter and have not noticed any differences with my Canon battery. They both seem to give me the same amount of time shooting. I think you'd be okay getting the third party battery, but perhaps some of the other guys have had poor experiences with those. My experience has been fine, albeit a different brand.

I've not had any problems with 3rd party batteries. Probably all made at the same place anyway.

I have Steringtek 3rd party batts for the 300D, it's the same type as yours. It seems to last longer than OEM, and it's 1800 mAh rated. To boot, it's only $11.99 each plus ship. http://www.sterlingtek.com/cabpbapaeq.html

I've found that Lenmar's batteries last longer per use (i.e. the additional mAh helps), but they seem to have a shorter life span than other brands I've purchased including the Canon that came with the camera. However, the price is cheap enough that it's worth it to me to have a couple extras in my bag even if they'll only last 1 year instead of 2 or 3.

I'll have to try that brand Kevin. I've never heard of them, but for $12, it can't hurt.