I put this in a reply, but thought I'd write a post about it.
The 911 has it's nasty reputation of being really murdery. This is both true and false. I've been working on learning the RR layout for a few years now. Progress is slow, but I have learned some things.
The important thing to know is that it's different. Yes, the majority of the weight is out back. Something like 40%/60% FR balance give or take depending on the car. Most cars are front biased, some really nice sports cars are 50:50, and some MR cars have a slight rear bias.
So what this means, if you've ever thrown a dart, or ever pushed a shopping cart backwards and jumped on, is that it's inherently unstable. That is, if there was zero friction on the tires and you pushed it down a hill, eventually the heavy back end would be in front.
But, fortunately, there's tires. And they provide friction. So stay within the limits of the rear tires, like you would in any normal driving, and you're golden. But what happens when you start pushing?
Factory tuning for almost all 911s is pretty biased towards understeer. If you're just going around a skidpad and slowly increase your speed, the front is going away first. Which, honestly, is the same as pretty much any other car out of the factory.
But what about non-constant speed? Well, here's where things get weird. Power on, the 911 really squats and plants the rear tires. In fact, that's it's trump card. It can get out of corners really, really well. I'd wager it can put power down with side loading better than some AWD cars. BUT, it also lightens the already lightly loaded fronts, and actually understeers more. I don't have enough power to break the tires loose into power oversteer in anything above 1st gear. LOTS of rear grip on power.
Braking is actually another strong suit. With little mass over the front, and the flat motor mounted really low, there's not a lot of pitch. My car has no ABS, so I have a bit of a hard time, but in concept it works.
So finally is the tricky part - lift throttle. If you're going in a straight line - not a problem. If you're going around a gentle curve - not a problem. If you're hustling - we have a problem. Lifting mid-corner transfers weight to those understeering front tires, which gives them grip. Weight gets transferred off the rears, specifically the taxed outside rear, which gives it less grip. A little lift will tighten your line. A big panic throttle drop can send you ass first. Going to fast into a turn is a no-no. If you end up going too fast into a turn, you CAN lift, but you must accompany that with a reduction in steering input. Lifting gradually greatly improves things too.
So what I'm finding is there is a "trick" to making the car go fast. Coming into a corner, you can use the inherent instability to get the car rotating. The light front end moves quickly, and the whole car pivots around a point that seems in front of the car. Not necessarily a big Chris Harris rally style drift, just good, quality rotation. As soon as you see daylight, you can feed in throttle. A lot of throttle. The rears will dig in and bite, the fronts will lighten and relent, and the car will straighten out and shoot forward. The trick is balancing the car right on that edge between oversteer and understeer. This concept is not different on paper than any other car - keep the car as balanced as possible. Just the techniques to get the car to the balanced state and keep it there are different.
The few times I do get it right, it feels much like balancing a broom on your hand. Concentration equals small corrections and a relatively drama free time. A break in concentration yields big corrections and a mess. Getting it right is extremely satisfying, like beating a tough boss in a video game without any cheats satisfying.
tl;dr - If you can get a shot in a 911 or any other RR car, don't be afraid. Just be aware that the physics are different, and therefore you pretty much have to start from square 1 learning how to drive at the limit.