FWIW
I like to experiment.

Tried the reverse and created a mapset with only the bitmap raster .img files - BlueChart G2 New Zealand North VPC416S.img - 280MB.
Removed ALL other mapsets, POI, waypoints, tracklogs etc.
Cleared all data from Dakota 20. This proved to be important. It is amazing how much residual data is stored in the internal hidden flash memory.

Results on my GPS:
The mapset appears to contains ONLY images. Satellite images and some black and white? (can't see much colour) close up harbour photos which are of no real use for my navigation purposes.

Tides - none.
POI - can't see any.
Other detail - can't find any.
Where To? - absolutely nothing searchable.

Remember this is only valid for my chart sets which now include:
hxpc024R G2i Australia NewZealand v3
VPC416S G2 Vision New Zealand North
VPC417S G2 Vision South Island New Zealand
VPC021R G2 Vision Mackay NW to Esperance
VPC410S G2 Vision Esperance to Exmouth Bay