If a forum newbie may contribute his 2cents, and I should also inform that I have no great, little, or modern kilt to draw personal experience from. From my never ending info gathering journey, the modern kilt strikes me as quite formal attire in general. To be honest, in the same way that I am not to be seen wearing a tuxedo, the formal attribute of the modern kilt is something I am not comfortable with. I also understand that, in the same way one may choose to wear patent leather shoes with jeans, if it works...it works...in the context of fashion. In my opinion - again, based on my own insignificant and personal journey - even the modern kilt is an anachronism. The idea is to revere and pay homage to the past; to show solidarity in the face of extinction (I also believe, for better or for worse, the Scottish contribution to western society gets lost in battles of extremes). If I were the kilt wearing type, or become the type in the future - and whether or not my people come from the lowlands or highlands - the unrefined and great constitution of the hunter/gatherer is a mindset more traditional to me. It's a matter of taste AND function, but if we subject ourselves to the public in the ancient traditional or modern national dress of the current or ancestral motherland, we should do so with respect in mind, because this manner of dress turns heads no matter what...here in the states at least. So it seems we should always be ready to inform as to the meaning and history - also be ready to inform someone to *bleep* off if they don't like it!
It's interesting to me, because the great kilt, with its bulk and difficulty donning, is more of an extravagant and eccentric formal attire, than the modern streamlined kilt, THESE DAYS that is. In practical sense, I would much rather plow through the woods in the modern style, rather than be snagged and hung up with the girth of the great kilt.
All this to say, be wary of the 'no true Scotsman' logical fallacy, and attempt to avoid it's gravity. We're all on the same team here.
To be objective, I can see the issue with being considered a 'costume wearer' as well...