12 knots is 13.8 MPH or 22 km/h. That's pretty much "average" for me here in Oklahoma, on inland lakes not a big deal at all. Don't know what that does on open water.
I've only used the Outback, so can't compare to the others, but I don't notice any real difference between calm at 12 knots. I eagerly await days with winds in the 16-20 MPH range, that's where I get the best waves on the lakes (wider / taller swells) to play in. Still no problem at all going straight into the wind. I've been out above that, even up to 30+ MPH, not as much "fun" for me as the waves get more steep-sided and close together, but I still don't have any trouble moving into the wind with the Mirage drive.
As Stobbo said, my most common experience when paddling with others is I have to idle along so they can keep up with me, though I'm rarely with any super-fit sea kayakers. On several occasions I've been headed upwind in winds strong enough that a paddler couldn't make any headway at all. I reached out and grabbed their bow handle and continued on my way, towing them into the wind! I always love their first-time reaction as we accelerate, a surprised "oh!" and a grin!

Oh yes, the Outback is a very wet ride into waves. One reason I enjoy it so much, it's great on miserably hot summer days. Not so much in winter though...