Hendrik said, "MC doesn't support reading BD ISOs natively, and you would somehow have to rig up mounting into a virtual drive by yourself."
and my reply to that was, "If this is so, then read the ISO wiki, and you can see how I got this idea... maybe it should be edited to be less ambiguous:"
...and then I posted the link and body of its text to show where I had gotten the idea that I could play BD ISOs in JRiver...
What I said is perfectly accurate. You have to manually setup a way to mount those ISOs into a virtual drive. The Wiki outlines the steps of one way how to manually do this, which will result in the disc being mounted by an external tool as a virtual drive. Not sure where there is any conflict with what I said?
Installing a separate application like VirtualCloneDrive (VCD) to facilitate this is as manual as it comes. Media Center cannot open an ISO. It needs additionally installed software for that. This is not "native".
Blu-ray folder rips, they play out of the box, just drop the folder in MC, and it'll play.
ISOs, require a 13 step process of software installation and settings changes as outlined on the Wiki.
Hence maybe you can see which method I would recommend.
Lets summarize:
Zero Pros for ISOs, and one big fat Con: Its complicated to setup, and the mounting process can be a bit whacky.
For Folders: Pro: Works out of the box and no whackyness. Con: Can be larger for 3D discs (although some ripping tools avoid that).