The historians among us could probably put a date (or at least a more definitive time period) to the distinction between 'dress' tartan and 'hunting' tartan. My guess, based on what I've read here and elsewhere, is that the distinction wasn't made until the mid-to-late 1800's, when the Victorian society started making all sorts of 'rules' about what should and shouldn't be worn, when and where they should/shouldn't be worn, etc. That was also partly based on the influences of the wool mills on the tartan cloth industry.

Prior to that era (and prior to the 1747 Act of Proscription which banned the wear of tartan), folk wore whatever was available.

As far as what a Highland noble would have worn - in any era - I haven't a clue. My best guess would include a linen shirt (as opposed to wool). I found this link, which may help.