I have driven one multiple times, my boss' brother has one and i usually see him once a month in which we take turns driving the Ralliart as well as the MS6. This is what we have both decided,
The Shifting mechanism- as far as paddle shifters, aren't too bad on the Ralliart, they shift quickly yes, but it will shift for you if it feels like you should be whenever it gets into high RPMs. The "Sport" mode, is just plain funky. It holds the gear in place even when cruising and you should really be the next gear up for a smooth ride. Just plain weird. Definately should have had a normal stickshift.
Interior- Very,mmmm, how to describe this, Man-Boy-ish. It's nice, don't get me wrong but it's just not as sophisticated as the MS6. It has accent colors on everything while the MS6 just keeps it classy with the black. The Ralliart interior is what you expect an 18 yr old kid with some money to get. Not very comfy either.
Stereo- yes, it has a decent stereo, but myself, my boss, and his brother all agree that the BOSE that's in the MS6 is FTW.
Performance- As many times as we have driven the cars, we haven't had a chance to get them on a line, but the Ralliart is a progressive pull, while as I'm sure you already know, the MS6 is just straight, Balls to the Wall, Rocketship, "here I go, hope you can hold on" unlike the steady "okay i'm speeding up, faster, faster, faster" that the Ralliart provides.
Hope that helps a little bit