For the peanut gallery:
The Garmin BlueChart for the US is fantastic in the Oregon or similar Garmin handheld chartplotter range (higher resolution/pixel count than the lower end Garmins, but you pay for that, of course.) However the US coverage extends to the BVI, but without the same resolution as in the continental US.
The BlueChart for the Southeast Caribbean fixes that. It provides detail in the Virgins that is comparable to that of the US chip in the continental US. Once again, you pay for that.
The small screen is a challenge after using the larger built-ins or tablets/iPads, but a device like the Oregon that is small, rugged, and waterproof and can be retained in a drink holder at the helm in bad weather has its advantages, like when you are threading a reef during a sudden tropical downpour in 100 yd visibility and can't read the bottom visually. That might be an infrequent occurrence, but it's nice be prepared for it.
Thanks for the excellent clarification. I look forward to trying the SE Caribbean bluechart chip.
Because of my overall distrust of any single chart supplier, I have really gotten to like plotting routes on my computer using the most reliable chart I can find (usually NOAA when in US waters), then transferring the routes to the Garmin Oregon. This gives me the opportunity to view the exact same route plan overlaid over two charts from different suppliers, and I believe that redundancy leads to better safety.
When we chartered last summer this became our normal MO - I would plot out the next day's planned rout in the evening, export the route to the Oregon, and we'd head out the next day. I liked it better than the boat's chartplotter because it was my own gear that I use on my own boat.
With this in mind, I put in a major effort today to convert the NGA charts (which I believe to be far more accurate than NOAA's charts in the BVI/USVI region) to a calibrated chart that can be imported to a chartplotter on my Netbook or an Android tablet (iOS devices are a lot more difficult to "sideload" content - charts, routes, waypoints - than the others, which I think over time will become a big negative for Apple). So far I have succeeded in getting the charts into a .WCI format that can be read by SeaClear II (without the menu corruption that I was having before), and I am 80% of the way there to converting them to BSB/KAP format that will allow using them in OpenCPN, which is by far my favorite free/low cost PC chart plotting program. The conversion is churning away as we speak. It's been a real learning experience installing VirtualBox on my computer, and Ubuntu Linux inside the virtual machine. I know more about this stuff than I want to know. But it also has given me a good view into how all these things work.
In the end, BVI is mostly line of sight sailing, so this level of redundancy is not really necessary, but I wanted to see whether I can do this myself.