I think it's nice that your IR readings are correlating what I would expect on paper. What I like to do is multiply the capacity times the C rating to get "relative amps" rA and the testing I've done over the years has proved to me that the pack with the highest rA typically performs the best under load:





Also notice that in this particular case that you're comparing apples to oranges because you're not comparing identical capacity and C ratings between packs... but I agree when it comes down to the bottom line on what you're spending in the comparison that it becomes justifiable for the comparison.