I am not running a comp currently. At one time, I was really thinking about converting my G17 into an open pistol but in the end, decided not to. So during that whole time of considering, I did a ton of research.
Anyway, what it looks like from a separate thread, titanium is the comp to go for. However, if I was to get into open, I'd use the KKM barrel with the 4-port comp for an ease of buying it as one piece and dropping it in.
My .02