I'm not impressed with the G37. Its really slow for what its rated at and I dont' see what the hype is. You can get a used G35 coupe for really cheap these days. You can't find a 5AT coupe?? Thats insane. Atlanta is over flooded with them. I loved my coupe, it just got small sometimes...I wish you were in the market for one in December, you could have got mine in prestine condition for real cheap. 

If you have any specific questions about the coupe, I can probably answer them...I know more about the coupes than the M35/45.

The AWS is what's rare not 5AT chik!

MY review of the G sedan... I love my car, but for what it IS, not what it isn't. It's supposed to be a sporty luxury car, and I think it does a good job.
Mt complaints would be in the refinement category. Interior doesn't scream 40 grand worth of car.
Paint sucks, but I think that's not limited to the G. Everyone loves the backseat, its comfy. Interior gauges look good, buttons and everything is intuitively placed.
Ride is smooth, but cornering suffers on this account. Acceleration is quick and smooth. High revs though, 70 mph is over 3k on the odometer.paddle shifters are cool, so is DS mode.
08 model gets ipod integration, that's cool from the threads I've seen.
If you can wait though, I'd wait to see if the '09 was getting the 3.7L and BBK. That would be sweet.  I guess I really need to drive an M to compare the two.

I can try.  I only drove a 2007 G35 Sedan on loan for one day, and here's my impressions (I've driven a lot of G35 Coupes though, before setting on the M - I need the room really).  The dashboard finish was not that great.  Big difference from the M: the materials, the finish on the cabin.  Don't get me wrong, it's good.  If you compare to a similarly priced "leatherette" (BMW's for vynil) 3-series, Infiniti is miles better.  The sound system on the 2007, the layout, the big screen, if very similar to the M - again, big difference from the competitors.  Also, the resale value on the G35 is outstanding, apparently the M35/45 is suffering on that regard a little bit more. 

What I like the G35 was that it was much more agile than my M35 - it is lighter, narrower, you have to really take care with not to snap your passenger's head - in a way, it exacerbates a problem already present in the M, the crispy in your face throttle response in low gears.  Even the 7 speed C-Class (07 and 08) I've driven couldn't match the acceleration in low gear.  Even the non sport version felt very sporty to me, although I could easily tell the absence of the RAS on the one I tested.  It really helps to go hard early on the corner exits and keep the momentum going.  Stylewise, I just wish the G35 sedan looked a little less tall amd narrow, specially when viewed from the back, just my .02 cents.  But that applies to the M too, maybe to a lesser extent - it could look wider from the back, I think.

Hope this helps.

I have an 07 G35 Sedan.  I rented a car about a year ago for a week, and was upgraded to an M35 (not an M45) because the car I rented was not available.  My general impressions were that the M35 was more luxurious in the interior, quieter, had more interior room, and had a larger trunk.  The G35, on the other hand, accelerates quicker and handles quite a bit better.

The AWS was available in 07

The "S" package may have bigger brakes than the journey, but it's not the 14" brakes on the g37.