Tonearm - 10:36 pm on Dec 28, 2012 (gmt 0)
I think it's advantageous, not necessarily from an Adwords perspective, but for (as RhinoFish mentioned) Content Experiments. We've run many successful experiments - some with higher conversion rates, some with higher average transactions, no discernable difference in conversation/avt but a substantial one in bounce, etc etc etc.
My most recent test yielded no statistically significant difference in conversion rate (very slight decrease from the original), but an increase of 31.4% AVT and +32.4% value per visitor. Depending on your traffic mix, you can also break out data by new/returning users. I've found it to be invaluable, but YMMV. If your current solution does all this, it might be a moot point, but I've found it to be extremely helpful.
I have an internal A/B split testing setup for that and I agree it's really helpful. It's tied into profit which is updated after shipment based on shipping cost which I think gives it a leg up on the CO in this context.
During mini-trends (like certain post-xmas buying), we see the CO move with the trend, chasing volume when it is converting, while we're drunk on rummed up egg nog. Top that!
Mine does the same of course, but the CO is faster because there are too many keywords for my script to process all of them in one day so I think you've got me slightly topped in that aspect.