Hi Seany,Just to add another tune or two to your list. I can still hear in my head a friend of mine playing the high notes on the tin whistle, with a little bit of harmony thrown in, on Come By the Hills, accompanying an amazing accordion player and singer called Mick O'Brien (who came out to Oz for a few years and then we lost contact with him). That was at a session at my place about 20 years ago.
That tune is still one of my absolute favourites.
Almost any of the harp tunes of Carolan sound good on the tin whistle.
Also there was a tune sung by Christy Moore. I think it is The Galtee Mountain Boy. But a lot of his tunes sound good on the whistle, too.
Helen (who has the volume problem in sessions too on Celtic harp)