I had a "non-trailering" sulky and it was very nice for backing up. In the video, you show a competitors sulky getting stuck under the mower as if you have a solution to that problem but you never show yours backing up.
The issue of always "being behind the controls" is a valid point but may not be an issue for some people. When you turn the WB with a "trailering" sulky, your arm away from the way you are turning does have to be extended and could cause manuevering issues, but only for the less experienced operators. I would not buy a sulky that "trailers" after owning one that stays fixed behind the mower.
2002 Silverado 2500HD Duramax/Allison ECSB
1996 Silverado 2500 ECSB
2006 Ferris 4500Z 61" CAT Diesel
2005 Exmark 48" Turf Tracer
2005 John Deere 647 Quik Track 48"