Aurora MS & QMS = never heard of it, don't know where to get it
They are Millenium discs and Millenium discs are made by Innova. They don't seem to advertise much. Does anyone know the address of their website? Dave? I used to throw Z Comets and a Z Buzzz and then went to Aurora MS and QMS (Q = candy version, regular Millenium plastic is Proline). the Sentinel MF probably has a lot more fade at slow speeds, while the MS is straighter. When the Coyote came out, it replaced the QMS in my bag although the QMS is probably a little more high speed stable. If i didn't carry an SB Roc, i would either go with the MF or maybe a KC Pro Roc (to fill the overstable midrange niche)...
i found the following descriptions of Millenium midranges --
The Aurora MS (Midrange Straight) may be the truest flying disc ever made. It has no rollover, virtually no fade, and surprising distance for a midrange disc. All you have to do is control the angle and watch it makes great right curve, left curve, or dead straight shots. Plus it's made from the same material as Millennium's long-lasting drivers.
The Sentinel MF debuted in Spring of 1998 as a limited edition specialty disc. But players started to fall in love with it. So in Spring of 2000, Millennium decided to make it a permanent part of their line. The Sentinel MF is unique among midrange discs. Its rare combination of speed and fade make it perfect for four situations: low ceiling approaches, skip/fade approaches, upwind approaches, and 'reverse S' approaches. It might be a little too much for newer players to handle, but better players will always want to keep the Sentinel around.