The fact we got a 64-bit update after years of begging is a miracle. If further testing is needed I'd say just take your time. We already have a big enough turd as it is so a little polish time won't really mean much in the long run. Since we've waited this long, what's a little more at this point
There'd be no need to patch the main client if turning on EAC was just a flick of the switch. If there was a merge, we'd have more than just connections to worry about. Conflicting names, clans, ect. We haven't gotten a warning so a merge isn't going to be the case for this patch at least.