I have finally plumped for the Dension Gateway 100 IPod interface and active cradle. Don't be fooled into thinking the dash display will show track names as text, it will not (and it runs out at track 99
Installation is a sinch:-
Unhook the head unit and slide it out.
Unplug the CD changed cable from head unit.
Plug Gateway cable into head unit.
Route IPod cable through back of dashboard (many scratches to wrists) and plug it into the Gateway unit.
Locate Gateway unit and its cable in spare space behind head unit and replace head unit.
I used a Brodit clip to fix the active cradle onto as this place it in readable distance so you can use the IPod text display mode to know what you have selected.
Gateway 100 allows selection of music by playlist/album/artist or cycle through all tracks. Changing playlist etc is a little clunky but straightforward enough.
Overall I'm really very pleased with the end result