A spec tire will be problematic in a multi-mark category because the size availability issue is even greater than if you have a number of manufacturers from which to choose.

Look - at the end of the day, you're opposed to the idea of 200TW tires because the status quo works for you. There's nothing wrong with that but sometimes the needs of the many outweigh the needs of the few. The good news for you is that SCCA rules-making has traditionally been pretty responsive to minority needs - if you've got the ear of the powers-that-be. When I go looking at current IT grids, I see pretty much NOBODY who argued that "National status will kill IT." Individual entrants come and go, and turnover in the club - in racing - is astronomical. The Club won't make a decision based on any kind of strategic plan, and a few connected people can pretty much kill any proposed change, so you're probably safe.

K