Thanks for the reply. I'll be using the GPS speed pulse stream as an input to a cruise control, used as a speed control on the wakeboat. As long as I have the speed signal, I'd also like to display the speed digitally. So if some handheld GPS provided a pulse speed output, it could serve all purposes and then I'd have the nice display you refer to.

Another person suggested I look into the Dakota Digital GPS-50-1, which looks interesting but costs more than the JEGS and Veethree solutions.