If that is the only difference (other than the branding) it may be that
you are paying the extra $100 for the production of the CDs and the
charts on the CDs can be downloaded for free. But there may be some
additional "bells and whistles" over what can be downloaded.

Some? How about LOTS of extras. The NOAA charts (raster and vector) are
good but they're lacking in quite a bit of added data. Being able to pull
up a picture of the harbor, on approach and aerial, has helped us a couple
of times when coming into ports. Then there's the street address, telephone
and other detail for various on-shore businesses. I've used that to call a
marina (after nobody came back on VHF) and ask "is it the pier with the
white building or the red one" and the kid that picked up the phone knew
which. Sure, it's an added 'frill' but one that's proved genuinely useful.

Rose Point's Coastal Explorer is an amazingly good piece of software. I
think it is the best product available for us with PCs on boats.

I concur.

SeaClear II with the RNC charts is a good low cost alternative for
electronic navigation in U.S. coastal and inland waters.

Eh, compared to Coastal Explorer/CNP, it's crap. Way too tedious to use.

-Bill Kearney