Yes, but the VMG directly upwind is always small. I an happy with 4K. If you consider that speed and the average of 5% you will get a difference of 0.2K in an hour or 1K in 5 hours of cruising. On other points of sailing the difference is much smaller and dead against upwind many cruisers will just turn the engine on. Big difference to a racer but not much for a cruiser.
But we should not forget that we are talking about two different drafts, drafts with a 20cm difference and that is a lot. Put there a single keel with 1.65m and it seems to me the loss in performance would be bigger.
I would love to see a comparison between the mono keel and the twin keel both with the 1.90m