0-60 in the low 7's, don't know 1/4 mile but do a search, I'd suspect mid 15's or so but... drive 'em both back to back and get your impressions. You don't drive numbers, you drive the seat of your pants (*unless you're racing/autoXing, in which case do the math).
FIRST: Determine what kind of driving you're going to do. If it's a 1-hour slog in traffic every day on rough roads or stop-n-go interstate, get the 6s - in an automatic. The MSP will be too stiff, too small, and too much clutching.
For me:
In comparison, the 6s is a big car. Big seats, big interior, big big big. For some this is "just right" - and it would perfect for me if I had that 1-hour commute (but I'd still clutch it! Too mucha purist for my own good). Great quality, stable, firm, handles great as a cruiser/Grand Touring car. Decent sound system. Big. Fast. Not (by comparison) "flingable". More for an autobahn than a road course or autoX.
The MSP is, by comparison, small, intimate, very firm (to the point of being "stiff"). It's more on the "quick" side of "fast", more for a road course or autoX than an autobahn. Seats are better sized to my frame (I'm a 5'9" road racing/MTB cyclist - fairly lean). Phenominal sound system for stock - and the "distracting" face can be very easily programmed to be very businesslike (the car magazines don't tell you THAT.) MSP doesn't have cruise control available except aftermarket - and I'm looking into that. LOADED with personality. Only endemic issues are some throttle surging (we're working on that) and some have reported the rear suspension clunking occasionally (and Mazda's working on THAT.) One frustration I have is that there's not a lot you HAVE to do with this car - the factory did most of the tuning for you.
Don't let a few thou separate you from the right car - how often do you make this large a purchase decision? Buy what's right. For me, it was the MSP, despite being a 40+ year old married father of 2. It was a great alternative to the Mini I wanted (but was too small). The 6 was just, I dunno, a little too "big" and "grown up" for me. Maybe the Mazdaspeed 6 would be perfect, but I suspect it'll be too loaded up/leatherplated/costly.
Good luck whatever you choose! Both are excellent cars.