I’ve only had two pipes commissioned (different carvers), but luckily for me both turned out well. My first one I only described something I had in mind, but other than finish and color, I was content to let the carver put his own spin on it. It fortunately turned out very well; some of the things he did “on his own” we’re surprising in a good way, and I really liked it.
The second one was like the OP’s situation: based on a photo of his one of his pipes. He riffed a little bit (a saddle stem when the photo had a tapered stem), but I like it a lot and in hindsight I’m glad he made the change. That being said, I feel he should have told me that first. I prepaid for that one. While everything worked out well, I won’t prepay again.