My 99 Suburban 1500 139,000 had the black ice feel often mentioned in threads when turning, it is a scary feeling when it jerks. I even saw a thread where a Suburban owners child who was a new driver flipped their truck because of it. My old mechanic disconnected mine and told me I did not need it. The wheel is very easy to turn with not much of a return to center feel, but I have been driving like this for about 7,000 miles and have gotten used to it. My son is a new driver and drives the truck like this. I am nervous about replacing the EVO because I dont want the new one to go bad while he is driving. I know I have posted several threads about small things wrong with my Suburban (We have a love hate relationship). I am concerned about this due to my son driving. Should I replace it? Any input would be great.

Sometimes it is not wise to disconnect anything on steering or saftey stuff.

There is several parts to it.
What part of it are you thinking about unpluging on it?
I would sugest getting a Alldata on line sub or a factory repair manual on it.
http://www.alldata.com/products/diy/index.html

And check with your dealer on TSB and recalls and ideas on it.
Your dealer should have test equipment to check it out.

The stering is electronic controled by the PS computer.
If there is a problem a good electronic PS capable scanner can check it out and read out codes.

MT 2500 brings up a good point. The EVO system is designed to increase steering effort at higher speeds unless the steering wheel is moved rapidly (evasive maneuver). My thought is that we got along fine without it in the past. The SWSS (Steering Wheel Speed Sensor) on my '98 Sub started giving the "herky jerky". I unplugged the connector at the pump for about 2 months until I could replace it. Like you said, I got used to it being easier to steer at all speeds. Since the SWSS replacement (4 years ago) all is good as designed.