Please, help !! my Slashes and Rustys, all got stock servos and I don't know anything about what the numbers on the servo specs mean, also why a Savox would be better than the stock one.
Please enlighten me.

its all about speed and torque. Lower transit time means its a faster servo. torque is the bigger the number the more torque (steering power).

speed:imagine your driving your car around a dirt road sweeping corner. The back end breaks loose and you start to counter steer. The back end is breaking loose and sliding out pretty fast but your stuck turning the steering wheel at a much slower rate than the swing of the back end. Your done, you aren't going to save it, it can't be saved, and you need quicker hands on the steering wheel to stay in control of the truck.

Torque:Your going through the same sweeper in your car. You've got super fast response and as the back end breaks loose you save it easy and continue accelerating through the corner. As you put more G-force on the front end by pushing through the corner your arms get weak on the steering wheel (powersteering is failing) and you slowly straighten out the wheels because you can't hold them turned. You end up swinging wide out of the corner and rub the guardrail all the way out of the turn.

I'm starting to see something; but what's best, high speed or high torque?

Both.. try a savox 1258TG, very nice servo for reasonable money.

http://www.amainhobbies.com/product_...ium-Gear-Servo

Honestly i didn't really pay attention to the steering speed or torque before, until I went to this track and saw an sc taking very tight turns like nothing, and the guy driving it told me to replace my stock servo for a "good one" (expensive one) and then I started wondering.
So, stock Traxxas 2075 digital servo:
Torque: 125 oz-in
Speed: 0.16 sec @ 60°
and Savox 1258 :
Speed @ 6.0V: 0.08 sec/60°
Torque @ 6.0V: 166 oz-in / 12 kg-cm

Is that a huge difference?
And the questions:
1. The difference between the two of them would be really noticeable?;
2. Is it going to improve the handling of my steering?;
3. The truck would be able to take sharp curves easier?

Or.... 4. Is just the driver who needs more practice?

.15 is just at the point of being difficult to drive. I would never pay for a servo with .15 speed and wouldn't settle for it.

the 125oz torque of your servo is actually pretty good. The traxxas are a bit heavier and probably require the torque but I'd say if your 125 or more you're doing good.

That .08 speed will be VERY noticeable.

Give it a shot and post back.

Might want to check out the Hitec 645MG. Run about $30-40 and is a great drop in replacement for the stock traxxas servo. I run these in 4x4 slash's and my stampede and its alot faster than the stock traxxas servos.

if needed you can step up to the hitec 985 or the 7955 which I use in my 1/8 bl conversions.

Hitec is a good option too, decisions, decisions.........

I disagree on the 645. The servo you have is better than that. Also the hitec is a analog servo, not digital, so if you use a premium radio you may need to drop down the signal rate to compensate for the servo.

Transit time: 0.24 sec/ 60 deg. @ 4.8V (0.20 sec/deg @ 6V)
Torque: 107 oz/in @ 4.8V (133 oz/in @ 6V)

this : http://www.amainhobbies.com/product_...ite-Gear-Servo

would be comparable to the savox 1258tg. Keep in mind that even though I link amain there are vendors out there as well as even folks on these boards that offer fabulous deals.

I just upgraded to better servos (Savox 1267/1268), the difference was huge to say the least, also got a better transmitter (m11x). I thought my driving needed alot if work, now it's a pleasure to drive. The best part about digital servos is the control you have, so easy to fine tune to your driving. I really struggled when my rear broke out, use to always over correct, now recovery is quick and easy. Very happy I up graded.

There is,.... one more reason to upgrade, although, I wanted to get the Savox SC-1258TG; but I might get the Savox 1267 better, what you guys think, I'll use it in my slash 4x4 and my slash 2wd

I think the 2075 is a great servo and does'nt "need" to be changed. Its a decent servo with decent specs. The 2056 isnt the best and if you plan on racing your rustler maybe a upgrade should be considered. But honestly you'll be fine with them.
I agree 100% youd be down grading if you lose your TRX 2075 to a 645MG