the copper versions were recently reviewed
here
to summarize:
"While I may be an old-school barb and clamp user, and I have had some issues with other compression fittings, the monsoon free center design is really a step above the rest in terms of eliminating or reducing the common problems associated with most compression fittings. The problem of loosing your finger tips and never quite getting things as tight as you would like are gone, you now have a tool to do the work for you and you have a very sleek and smooth look that is unmatched. I’ve been generally very impressed with these monsoon compression fittings and suggest you give one or two a try before making a decision on what to build your system from. With fittings, I would always suggest trying one or two yourself first as you do kind of buy into a style and it’s worth making sure with one barb sample first. The monsoon compression fitting is the first to really change up and clean up the looks of compression fittings and they have also improved several areas of performance and improved the user experience while doing so. I recommend them very highly."