According to their press release, there are more than 30 different varieties on the grounds and I would guess a least a few would be among the 12 native species. The course itself was developed on property that was a former nursery and among the plants the nursery specialized in were azaleas. So I'm sure lots of hybrids as well.

The typical azaleas of public gardens in that part of the US are the large-flowered "Southern Indicas", which are not hardy in CT - and in fact the site of the golf course was where many of them were introduced or bred: http://www.plantsrescue.com/tag/azalea-indica/

Several hybridizers of the past 60-70 years have focused on breeding hardier varieties that look similar to the indicas, and that would be what you would want to seek out.

(as happens on the web, an otherwise useful source of information has some flaws. There's no such climate designation as "Humid Oceanic" LOL. The Southern Indicas grow in the warm temperate through subtropical parts of the world. I saw some in Australia, for example, and also saw them at the Huntington in Los Angeles)