The difference is that you have the under-deck quadrant drive, and they've got a wheel pilot unit... so yours will probably be a lot more robust.
Wheel pilots tend to be fairly light duty from what I've seen...the underdeck ones are much more reliable.
But SD look at post #21 directly above your last post. I don't have a quadrant drive on this boat. Look at the picture, it's Raymarine wheel drive and S1 head..
As I said I have owned above and below decks units, by owning 10+ cruising sailboats over the years this happens. How do you think I got all those anchors? The accuracy of this S1 beats them all regardless of the fact that I have a WP.
While I agree 150% that a WP is far less robust than a below deck unit I have used them in some pretty nasty stuff and they've held up well.
Currently, my wife, daughter and I only coastal sail due to other commitments and rarely even sail over to Nova Scotia any more. I would have no problem using my S1 for that trip and I've done it on many boats with WP's from both Simrad and Raymarine..
Last summer we sailed a 78 mile virtually dead down wind run in 25-30 knots and 4-6 foot chop, very typical coastal stuff, and the S1 steered the whole way no problem. All I had to do was trim sails....
Set up is key though..
If you're coastal a wheel pilot is fine. If your off shore get a below deck. If you're cruising get a wind vane too!!