I tried 9 speed friction on a vintage frame I was building up. I ran friction shifters for many, many years. But I found it fairly difficult to accurately shift a 9 speed cassette with friction. The spacing requires a lot more accuracy and I got ghost shifts. The ghost shifts were caused by the RD not being quite right on the sprocket, but I didn't hear the noise that would have been associated with that in smaller cassettes and less flexible chains. At least that's what I was thinking. If I heard the noise, I'd trim, but even when I trimmed it to be quiet, I would still occasionally get ghost shifts.
I switched to 8 speed (same hub/wheel) and it was much easier and pleasant to ride, less fiddly. Same range too, in my case 12-28 (or 11? I'd have to go out and count teeth). I don't know, maybe I would have become more proficient and comfortable with the 9 speed, but like I said, it wasn't my first go-round with friction shifting, so I accepted that I didn't like it.
Anyway, something to think about.
In the end, I found and switched to some beautiful Campy (this is a Campy drive train) indexed 8 speed downtube shifters on eBay which weren't very expensive which work very well.