Just curious, why aren't you going back to a TC? (MFK)
I'm not a huge user if diaphragm calls, prefer hand calls honestly over diaphragms, although I like to think I can use dia's very well. Will Horting makes a great horn howler, and if you're looking with someone with some history in the biz behind them, Rich Cronk is still turning them out too. I don't have one personally, but I hear great things about Tony Tebbe's horn howlers as well.
I picked up a set of TC's at a garage sale a while back, the gal selling them thought they were her husband's turkey calls. I've been tempted to get a few MFK's, but haven't been so motivated about them.