"Since both kits support identical optimized values, I’d say that either Corsair was being cautious or Mushkin reckless. I’d love to hear your opinion in the response thread."
How about what's inside ? I see GPU reviews, PSU reviews, MoBo reviews where the unit is torn down and each part identified ..... how come reviewers don't look at whose modules are used ? I think that might just answer your question above.
One thing I noticed with DDR3-2400 was that Corsair VPs, Corsair Dominators and Muskin RL's both marketed sets for some time with 10-12-12-28 timings .... I had opened up both the VPs and RLs and both used Hynix modules. Then after a while, the VPs dropped to 10-12-12-31 and in searching for the reason behind the drop, I found out that (after version 4.51 IIRC), Corsair switched module suppliers. Mushkin still continues to offer 10-12-12-28 and I can personally confirm that they are still Hynix modules. Soon after the Dominators, also dropped to 10-12-12-31 leading me to believe they also switched suppliers.
My assumption at the time was that they each used Hynix in early years while production lines were young to maintain desired yields, but as lines matured and yields started to exceed demand, it made sense to switch to less expensive modules.
So.,.. to answer ya question, one of the possible reasons for the different performance observed could be eliminated if ya popped off the heat sinks and identified whose modules are underneath.
When I see DICE / LN2 users looking for those record breaking OCs, one of the things usually found in the siggies is RAM w/ Hynix modules at crazy voltages ... highest i can remember for DDR3 was 1.94