Manglespamming, with Glyph of Mangle instead of Glyph of Shred, is sup-optimal. It is slightly easier, however it also results in somewhat less DPS. It's still viable, but you won't be at the very top of the meters doing it. If it's really too hard to press a different button once a minute, I won't stop you from manglespamming, but I don't recommend it.
However, learning to use Shred is relatively simple, and you will be far more effective in the long run.
Stampede and You
Stampede is a new talent added in Cataclysm that reduces the cost on Ravage and removes the stealth requirement following Feral Charge. Unlike Vanilla through WotlK, Ravage does not suck, so this is a good thing especially when combined with the crit chance boost on high health mobs from specing into Predatory Strikes.
With 2/2 Stampede, Ravage costs zero energy, and the buff lasts a reasonable amount of time. With this in mind, you should *never* open with Ravage. Get Feral FF up first, since your free crit Ravage will hit harder. If Tiger's Fury will come off cooldown while your Stampede buff is up, burn energy off so you do not overcap if you Tiger's Fury, and then TF->Ravage to boost it's damage even higher.
Tiger's Fury and You
Tiger's Fury now increases all physical damage done for the duration of the buff. This is a considerable improvement over the previous incarnation where it merely boosted weapon damage. Also unlike in WotlK, Berserk no longer clips the Tiger's Fury buff, so you are now free to Tiger's Fury directly into a Berserk without losing DPS. As noted in the "Pro-tips" section, when it comes to bleeds, the effect persists for the full duration of the bleed assuming it is applied when Tiger's Fury is up.
When considering the damage tradeoff to Tiger's Fury-ing bleeds, the thing to keep in mind is that the moment you lose over 15% of the bleeds duration worth of uptime, you are losing DPS.
Rip with Glyph of Shred breaks even at 3.3 seconds worth of downtime.
Rake with 2/2 Endless Carnage breaks even at 2.25 seconds worth of downtime.
What this means in practice is that you can Tiger's Fury every other Rake for a minor DPS gain. In theory it is also possible to have Tiger's Fury a fair number of Rips but combo point management gets considerably more complex. Currently I view it as "Yes, you should Tiger's Fury every Rip, but don't stress over it if you can't", especially because trying to maximize this requires using Rip/Tiger's Fury with sub 100 msec precision and monitoring the TF cooldown and Rip tick timer in addition to other things.