I used one for 18 months at a previous band and liked it a lot, they're very well made and good to play, you can really fill them. They feel heavy and well made, unlike some I've tried where the metal is thinner and seem to make the tone shrill. The only thing I ever heard against them is a guy who reckoned that they have issues with Wick mouthpieces, something to do with the way they fit in the leadpipe making 1st valve notes sharp :?: . Can't say I ever noticed it happening on the 10 we had.
I use a large-bore Sovereign now which is equally as good, but I did like the laquer finish on the Cortois better than silver.