I know it is ancient but I only went with ST40 as I was going speed and depth only to keep my instruments simple. Value for dollar seems to be there as the display is larger and does what I need. The ST60 display was smaller and way more expensive. I am in to speed and depth for just a hair over $400. ST60 was almost double that.

I just have never really felt the need for a masthead wind instrument. I don't really need to know accurate windspeed, just how the boat feels.

The only Garmin handhelds that support NMEA appear to be the ones with an old serial output cables versus USB. For whatever reason, they will only carry their proprietary Garmin signals over USB.