Aha. My current bar ends look just like those, or they would if you were to chop about two thirds of the last straight bit on the ends. I hope that makes sense.

So I guess if they don't work with the trekking bars then I can happily use them on the straight bar with my existing bar ends. I like the idea of drop bar ends but I can't find any available anywhere.

I'm just reluctant to do the bike fit (which I suspect will involve buying a new stem) and then have to do it all again (with possibly another stem) a bit later if it doesn't work out.

Perhaps I just need to man up and deal with it. I do appreciate the input though.