The GK Pickups are 'analog'. They are made up of mini humbucker pickups.
Roland Guitar synths have ALWAYS performed much better triggering 'internal' sounds as opposed to external synths via Midi.
The now defunct Axon units (out of business) were much better at triggering external synths as they used a very different means for converting pitch to midi.
The upcoming Fishman Triple Play will probably be a groundbreaker. Its designed by the guy who did the Axon units. Wirelss Midi Converter for $300.
Ive owned the Gr30, gr33, vg99, and gr55. Out of all these the gr55 performs 'best' of the Roland units when it comes to external triggering. Its still not great however, and as others have mentioned, you need to adjust your technique and I recommend using the Midi Filters included in Sonar. Theres one especially helpoful for Midi Guitar:
Process>Deglitch
This makes it incredbly easy to filter out the little transient blips and blaps you get with Midi Guitar. Try it, it helps alot!