In edition 34 of the farmers magazine Boerderij (May 26th 2009) appeared an overview of several popular RTK guidance systems in The Netherlands.
The independent review was done by four students of the Stoas Hogeschool in Dronten. Our SBGuidance system came out on the first place.

Here is a short overview of the scores on a scale of 10:

SBGuidance Auto: 7.8
Trimble AutoPilot: 7.2
Autofarm Autosteer A5: 7.0
John Deere AutoTrac: 6.8
Agrocom Outback E-Drive: 6.6