MP3 in an E60.. Grom v Dension v ??

So research has shown none of the add on systems  at any cost will get cover art onto my CCC iDrive, (8.8inch Pro dual slot with 6CD and MP3 ability coded, aux in behind the drivers bolster but no USB in the cubby hole as the later LCI optioned out) to achieve that I need to tear it out for a CiC system or to go aftermarket which I dont see as cost beneficial, looks trick tho. 

I dont need more bluetooth (car has it) or phone, or bells and whistles at all.. Not my thing.. I just want a big thumb drive, or Ipod classic, wired in for use through the iDrive. Not so much to ask is it ?? I also want to select and navigate through the idrive, not on the iPod, stealth install. 

I have no issue with re-encoding to any standard, or to creating a special file / folder format, or tagging. I would really value gapless (even if that needed to make album playlists) and browse by album artist (or at least composer as I do with an iPod). Lots of DJ mix albums. 

Grom audio looked appealing price wise but I now understand it will see your top 5 or 6 root folders as emulated CDs ?? So that means I cannot simply browse Artist -> album -> play.. I need to know where on each CD the artists are. Thats a non starter, its too ugly a workaround solution. 

Does the Dension 500 operate like that also ?? Cant I simply have one source with a collection of my music somehow, and access it via the iDrive control wheel, and steering wheel buttons ?? A source, with my files, that can be browsed and played ?? 

If it does work that way.. What quirks or drawbacks does the dension have when using MP3 on a USB or Ipod ?? Its a decent amount to spend for only that ability, would hope it worked without issues but learning this isnt that simple on iDrive systems. Posts about how clunky the standard BMW interface is for MP3 seem off putting. 

Really looking for real user input, done about as much digging as I can.