To me, your GPS choice depends on what data you want.
If you are only interested in a spot/average speed then almost any water resistant/proof device will do.
If you want tracking data for use with GPS Action Replay
www.gpsactionreplay.com (et al) then you need a GPS with at least 10000 track points. 10000 track points at 1 per second is about 2 hours 40 mins of tracking data or you can go for 1 track point per 2 seconds and double the duration but obviously halve the resolution.
It does not appear that the Velocitek has track points.
http://www.velocitekspeed.com/product.html