I recall reading in another post that a MKI with 56GB of disk may run out of ram to hold the FID tags, can such a thing happen to the MKII, and what is the limit of a stock MKII Empeg car with v2.0 firmware?

Also what can the MKII be upgraded to again?

It's not the disk space so much as the number of tunes on the player. If you encode all your tunes at a high bitrate, then 56 gigs will hold fewer tunes than if you'd encoded them at lower bit rates.

The number of tunes that gives the problem also seems to depend upon how much tag information is filled out, such as data residing in comment tags (if I recall correctly). So the exact number of tunes isn't the same for any two players, either. But I've heard reports of some players having database-size-trouble when the number of tunes gets into the teens of thousands.

I think I smell the need for a potential feature in empeg management software.

Have the software analyse the FID info and calculate the needed RAM on the player before loading new tunes, and maybe estimate remaining space for FIDs via the trend in track info per song.

I wonder how bad the lyrics added to mp3s affect this

comment tags being everything other than the basic tune name, artist, album, year?