It's not a merger, DT didn't buy Columbia. DT has been having their balls manufactured by Storm for a long time now, but with the 44 Magnum, Storm couldn't give them the production capacity they needed in the timeframe DT wanted. So they switched.
Future DT equipment will be made by Columbia, current DT stuff that's made by Storm will probably continue to be made by Storm until it's discontinued (which, judging by a recent discontinued list, is almost everything). Columbia doesn't have access to DT technology like the Soaker coverstock, so you won't see a Soaker-covered Action. Nor does DT get access to Columbia's technology, so there won't be an epoxy Vendetta.
Search the last few weeks on the DT forum, you will find more info than you ever wanted to know.
SH