Actually, Subaru has at least 3 different AWD systems, all marketed by Subaru as "symmetrical AWD" and which one you get depends upon the model and even the trim level. There are advantages and disadvantages to all of them but their newer systems have moved to computer controlled electronic multi-plate clutches to change torque distribution which has important advantages including a faster reaction time. A common misconception is that the microsecond delay that occurs with the Mazda system somehow cripples it at low speeds or on slippery surfaces. That's just not true (regardless of Subaru's implication otherwise).
I haven't compared them myself, but the video's I have seen and every single comparison of the two on reduced friction surfaces indicates otherwise.
One primary problem with the purely mechanical viscous center coupling used by Subaru on many models/trims is that it is much slower to transfer torque via purely mechanical means (no computer) and it is incredibly inefficient and robs power, one reason why many Subaru's feel so gutless in real life relative to their HP ratings and why Subaru is transitioning to computer controlled multi-plate clutches for torque distribution when slip is detected. Also, on extremely slippery surfaces this type of system creates a small and unavoidable amount of "binding" which actually makes the car less sure-footed negotiating icy corners. It can actually induce a slide. The Mazda entirely avoids this issue which is more important from a safety standpoint for almost every driver out there than some small advantage in being slightly better at hill climbing.
Also, Subaru has recognized the advantages of front-biased torque and are designing their newest systems to bias the torque to the front wheels when no slippage is detected. But all wheels are still driven full time which is still quite wasteful and robs power in normal driving which is over 99.9% of the time for almost all drivers.
I dunno...my Jeep was like that, 52/48 torque split and it got it's EPA rated mileage on the freeway, which was within about 1mpg of the non-AWD version. Mazda gives up 2mpg on the freeway for their AWD...
Read about the details here if you don't believe me:
http://www.cnet.com/news/not-every-subaru-all-wheel-drive-system-is-created-equal/
With computers becoming faster all the time, and with electricity moving at the speed of light, electronically distributed torque systems act more quickly than mechanical means and this has been true for a number or years now. In recent years, the resolution of wheel sensors is constantly increasing and electronic clutches have become even faster and more progressive, further increasing the disadvantages of purely mechanical systems and viscous couplings(which is why Subaru has been introducing these items and adding complexity to their Symmetrical AWD systems for a few years now. While complex hybrid systems using both electronic clutches for lightning fast torque redistribution and hydraulic center differentials for more flexible and full-time four wheel drive have some small advantages in terms of sheer climbing ability, they have no advantage, and some very real disadvantages, in terms of simply driving on icy highways.
And then there is the weight, complexity, expense and fuel and tire wear inefficiency of full time AWD to be considered. The Mazda system is mechanically simply and lightning fast, 2WD 99.9% of the time for fuel efficiency and tire wear advantages and yet is AWD when needed to avoid the problems by only having FWD or RWD. I also like that the Mazda system is non-binding on icy roads and thus will never induce a slide in a fast turn due to slight binding between the front/rear. Yes, the Subaru can detect the slide and apply corrections (if it is one of the newer systems with computer torque vectoring) but this kind of slide on very slippery surfaces is difficult to detect by wheel speed sensors and, once initiated, it may be too slippery to correct.
Allegedly my Jeep could "bind", as it has ELSD's front and rear, but I never experienced that. Even power-sliding it around corners in the rain with the TC on. Now I have read some owners have, and recommended being very careful lest it upset the vehicle. Again, that said, I agree with you. I prefer a non-binding potential myself. However...what harm is binding...it's just shock-loading on a slick surface. Kindof like Mazda's AWD 
Both systems have advantages and disadvantages but, IMO and experience, I like the "hands off until necessary" approach of the CX-5 over the viscous center differentials.
