"Enable bitrate field" changes nothing (so 8P: P+/S+; PP: P+/S- like before). Note: I have to set "Use flat URLs" otherwise I do get an error in PP, but I guess this has nothing to do with the problem.
However, finding the correct DLNA server settings is only the minor issue in my opinion. At least there is a working combination (using 8P instead of PP).
But my point 4) is more important, I think, and has nothing to do with the DLNA server settings. MC itself cannot handle the Denon correctly and there are no options (at least I know of) to correct this (as compared to the DLNA server settings, where there are options). 8P must do somethings right, which MC itself does not...
By the way, there is another issue, which I think could be solved very easily:
The Denon AVR4311 has an always on network card. When using 8P or PP I just have to start playback and the Denon switches on from stand-by and starts playing. Veeery convenient. The start-up of the Denon takes a while of course (around 10-15 seconds), but the apps can handle that and I guess retry the play command for long enough until the Denon responds.
Not so MC. When I do the same with MC as the controller, I get an error message (on my server PC, where I do not see it normally) that the device does not respond or so. I think this is just because MC does not retry long enough and gives up too early. Could this be changed? It's a small thing but makes live much easier (no need to get the remote to switch on the receiver, just take your phone and press play).
--- This issues was added upon a very urgent (and pressing) request from my family members ;-) ;-) ;-) ---
Just a personal note, why I think point 4) is more important:
I tried several DLNA apps for iOS and did not find any combination (server, controller, renderer) really working good. Most DLNA apps are way to complicated to use, none is working reliable (playback stops randomly after some time, sometimes I had to restart all devices to get it working again, etc. This got me constant complaints from my family. My personal feeling is, that the DLNA standard is the real problem and does not work reliable if the three roles are on different devices. So, I changed to JRemote, to eliminate one role (server and controller is combined in MC), which is like heaven on earth, as it has a very good UI, and works much more reliable (complaints almost stopped ;-)). The only issues are the start-up thing and the seek function, which I really regard as important, especially if you listen to 30 min tracks or audio books.