Sort of... Thanks for the suggestion!
I researched the Canon 20mm prime as a direct comparison to the Voightlander and my long heavy 24-70 and found that it was not sharp and still pretty heavy, not short either. Ramon above points out the value of the IS (and modern IS is better) so perhaps I should compare weight and size of the smaller, slower Canon 24mm prime.
I do have the super-sharp Canon 24mm f1.4 and it is shorter but almost as heavy as the 24-70 v2 (8oz difference.)
The person from whom I bought the used stabilizer confirmed for me that the sway I saw was due to the physics of initiating movement in a mass (camera/lens) distributed across a longish distance between back of camera and front element. A big front element weight hurts a lot among the factors influencing the motion seen on video.
BTW, this YouTube video -- shot with a different [low-end like mine]stabilizer brand and that Voightlander is pretty impressive for the non-Hollywood types and clients like mine. Check it out:Canon 5D Mark III with Voigtlander 20mm Lens (Tested with Glidecam)
Takes a little while to get to the footage you want to see, but you can see him RUNNING while capturing (by showing his shadow.)
So I have two questions to investigate today: 1. is weight/size going to be MORE important than sharpness, and, 2. is 28mm wide enough for the rooms I will do for at least my first gig (which has to pay for at least a part of the added junk...)
...and I realized that sway aside, I can use another lens I have here to establish -- using my little house -- if the Voightlander 28 would be OK and save me a couple of hundred over the 20mm.
Even if... I bet I eventually get that newer 16-35. Results are quite good.