Late this summer I picked up a Contour+2. I built a PVC camera mount with similar placement to the Americas Cup center stern camera. First trip out I forgot to format the memory card.
Second trip out got to the boat ramp only to discover the government shutdown somehow included the extra funding required to barricade off all access points to the lake I sail on. And that ended my summer.
I can tell you one thing though. The software that comes with the Contour+2 is very limited. You can overlay a few stats on a video that for some reason you can post to YouTube, Vimeo, or their website, but you can't save to your own hard drive. My next purchase will be a copy of DashWare ([url]DashWare.net[/url]) It's about $50 will read the files the Contour+2 creates. You can do a lot with creating custom overlay gauges, importing, and analyzing data in many formats.
I'm thinking your best setup would be the Contour+2 camera, DashWare software, and maybe Excel if you need to do some fancy math to create data for some of the possibly more advanced gauges like VMG.
One more nice thing about the Contour+2 is that you can take GPS data at 5 Hz vs. the 1Hz a lot of GPS loggers record. For a video overlay getting updates only once a second is really annoying and probably wouldn't have enough resolution to really show how you did through a tack.