Well, I was planning to check whether the attached device is a Nook (easy enough) and if so, check for existence of directory
/screensavers or
/my screensavers in internal memory root.
If the former exists then assume a Nook STR, if the latter then a Nook original. If neither then it's an "unsupported Nook" for my purposes.
It's not exactly sophisticated
but I'm hoping it may get the job done. I used something similar to detect whether a Sony PRS600 has PRSPlus loaded and whether a Kindle has been jailbroken.
Oletros has agreed to test the new version for me but I'm not sure when he/she'll have time.
...the perils of trying to do things without the necessary equipment. It's rather frustrating...