it wouldn't be a simple Registry Setting change telling MC to use Gecko (assuming you already have Firefox installed) instead of IE, which is what EpF was hoping for I suspect.
Yes; I was hoping that there was some way that, with minor effort on J River's part, you could tell MC that you have FX installed and to use that instead of IE. I remember sometime last year I discovered that you could do that for FeedDemon by jumping through a couple of pretty minor hoops. (I just did a quick look for the link but couldn't find it). It worked just fine for me.
I wouldn't expect JRiver to replace large amounts of built-in stuff, but I assumed that MC was mainly making use of my already-installed IE browser...
That does make me wonder if it is costing J River much to use IE as part of MC - what does it cost to use FX?; they might save some money. I'm totally out of my depth on this subject, though, so forgive me if I'm not making any sense!