Despite Dale's reply, by and large I think you are right. The Dunlop (DoT and NZ road legal) tyres I use come in Soft, Medium and Hard. Many of the other BMW series guys also use them and the tyre life, particularly the Soft and particularly at Taupo can be alarming. I screwed out a Soft set in a weekend of qualifying and 3 races before changing back to the mediums. However they are quicker and the tyre performance deteriorates noticeably as they wear so if your budget was not an issue, guess what?
The Hankook in question is a G51 compound and in slick form will last V8ST long format races with no deterioration and there are several class A BMW guys who use second hand V8ST tyres, they do seem to deteriorate with multiple heat cycles but don't wear out. The question of going away from DoT tyres comes up each year at the BMW series AGM and the argument for slicks is always a cost based one, many of the front running class B guys would love to be able to run the Hankooks as well.
If there is no series rules, eg ERC or BMW (or indeed HMC) that specify DoT AND NZ road legal then I can't see any reason why the Hankook is any different to the Hoosier for a meeting such as NZFMR. Both are a DoT compliant semi race tyre, both have reasonable tyre life and are (relatively) cheap.