Gary Casey wrote...
>>>One reason I opted for an ES is that it has a sister ship that is certified and
anything really bad would presumably be corrected on both. Then I learned
that the certified version has a completely different airfoil, making stall
and spin information non-transferable. Further I learned that the IV and ES
(and the 320/360?) share the same airfoil - the ES just has a lot more of
it.>>>

Two stories that convinced me that I will use a lot of altitude and work hard to keep the ball centered when it comes time to calibrate the AOA indicator in my ES.

1. Around the time of purchase, I asked a company rep how certification (leading to the Columbia) was going.  He mentioned that they had decided to redesign much of the plane, including the wing.  When I asked why they changed the wing, he said something like "on spin number 17 we lost a lot of altitude."  I inferred from the discussion that they were having trouble with spin certification.  As I understand it, they chose to redesign the wing for the Columbia so that it is spin resistant.  The Columbia apparently does nothing but mush on stall, like the well-coordinated stall in the factory ES described on this list the other day. 

2. A member of my local EAA chapter was at 10,000 feet conducting power-off stall testing in his 320.    The pilot was a former airline captain with over 20,000 hours, an FAA examiner, and lots of time in lots of small planes.  As they approached the stall, a wing dropped with very little warning and they found themselves in a spin.  It took them more than 4000 feet to recover.

My conclusions from these and other stories: i) a spin in these planes can cause a large altitude loss, and recovery is not guaranteed (this is emphasized in the ES manual); ii) an uncoordinated stall in these planes can develop into a spin pretty quickly, or at least quicker than we Cessna flyers are used to; iii) absent stall strips and/or an AOA indicator or some other stall-warning device, these planes tend to provide little warning of an impending stall.

How to practice given these stories is a personal decision.  I know that when I finish my ES,I personally won't practice stalls at 3000 feet like I do in a Cessna.  And I imagine I'll have a heightened sense of awareness about keeping things coordinated.  Perhaps the personal minimums will fall some over time with experience.