Having just returned from my BVI charter (and not wanting to fully let go of the memories), here's a brief summary of my navigational experience down there.
As I previously mentioned, I installed the newly released Garmin Bluechart app (free) and ActiveCaptain database (also free, but registration required) into the iPad. Just prior to going I decided to spring for the $45 North America Garmin Bluecharts. This was not required, since the ActiveCaptain data was still fully useful without the marine chart, but for $45 I was willing to give it a try.
The Garmin charts are useful, but since I did not have the Garmin WiFi network on the charter vessel (nor do I want to install one on my own boat), there appears to be no way to offload routes, waypoints, and tracks onto other devices. This will limit the functionality going forward.
Prior to leaving, I also borrowed a Bluechart SD card for the area and loaded into my Oregon 400c (thanks Frank!), which proved to be extremely useful. I quickly fell into my normal routine of plotting the next day's planned route on my laptop in the cabin (using OpenCPN with the NGA charts that I had calibrated for digital use), then using MapSource to transfer the routes to my Oregon for use in the cockpit. I installed the Oregon handlebar mount at the starboard wheel so I had the route available in the cockpit at all times.
I need to say that I consider the availability of pre-plotted routes to be a critical safety item when navigating unfamiliar waters. No matter how good your ded recking skills may be, when you look out along the hazy horizon in a place like BVI, it is impossible to tell whether a certain feature in the distance is a cove, a bay, or a cut between islands. There were numerous times when I would have missed a critical turn if I did not have the little purple line telling me it was time to turn. For example, when I left Marina Cay toward Guana Bay, the Camanoe passage came up much faster than I expected, and I just know that I would have wandered into the rocks between Beef Island airport and Little Camanoe (which were on Sunsail's prohibited list, and we had been explicitly warned to stay away from). Things just don't look the same as you expect them to from the chart, and that little purple line is what saved me there.
The Garmin iPad app may find some eventual use in my normal route planning, but for now OpenCPN is much more powerful. I prefer the precision of clicking a mouse on a screen, and not sure I will get to like tapping on a screen with my finger. Also, the more robust sailing in BVI caused more water in the cockpit than I was comfortable with the iPad. On my own boat on our protected river, my cockpit stays much drier, so I have a bracket to mount a netbook, which allows display of AIS targets onscreen using OpenCPN. Until there is an iPad app that displays real-time AIS targets from my boat's NMEA data, the iPad will be of secondary use.