If you have ever split off a site and then later re-merged those sites, could you let me know your experience with your rankings?
Back in late 2010 I split my single ecommerce site into two different sites (we will say Site A and Site B).
Site A has seen a slow, steady decline in traffic, but DOESN'T appear to have been hit by any penalties.
Site B initially started to grow rankings, but it was hit apparently by a Panda update in March of 2012 and by the May 9th "Phantom" update and May 22nd Penguin update.
I am thinking of moving the ecommerce section of Site B back into Site A to primarily escape whatever penalties I might have.
Also, many of the products CURRENTLY on Site B actually got links when they were on Site A, and I 301 redirected those links to site B. I think it is possible that somehow those 301 redirects are not carrying the same value from Site A to Site B, so possibly changing them back to their original pages might help?
Thanks in advance for letting me know if you have tried something like this and how it worked out.