I've only had the Xplorer topcase, really good quality, and I'm considering getting it for my MTS aswell. The black one would look so much nicer than the original Givi one.
I'm not so sure about the sidecase though. I think Ducati has made the most well hidden case mounts, and with the extra clamps, the Ducati cases are ok (And looks fairly good on the bike), so I would prefer not having the extra scafolding (Even though the Hepco&Becker doesn't look too bad).
About the mount for the topcase. The "original" Givi topcase requires an extra supportframe to install. The Hepco&Becker only requires the 4 screws. Wonder if it's solid enough without the extra frame like the Givi?