I may be opening a can of worms here...but I don't think that it's disrespectful at all to wear a regimental badge (actually, this regiment sadly no longer exists as a whole, as it was amalgamated into The Royal Regiment of Scotland, after being amalgamated into The Highlanders). I think that if it was a current regiment that still wore the badge, then maybe I can see where it might be construed as disrespectful, but to wear one that is no longer worn..I see it more as keeping the tradition and memory alive. Sort of a memorial of sorts if you will. I myself wear the uniforms of (WWI and WWII mind you) the Liverpool Scottish, which no longer exist except in the cadet training form. So as long as your not trying to pass yourself off as a member, then I don't see it as a problem.
Just my tuppence worth.
Oh yeah...and I ALWAYS think there's room for more horse hair sporrans in the world!!

Chad