Sensations of prostate stimulation

I just ordered the Aneros MGX. I read most of the post to the forums before purchasing it. I noticed that in order for this to work you must first become in tune with your body and use your PC muscles to control it. Anal stimulation is nothing new to me but prostate stimulation on this level is. I already know how to control my PC muscles. A few times during anal play with a small probe toy I hit a spot within myself. This spot created a sensation within my penis as if a tuning fork had been struck inside my penis. A vibration from within. The sensation was so different I didn't know if it was something good or something bad. So I tend to stay away from that spot. Is that feeling I'm describing prostate simulation? Also I have had a couple of times when I shook uncontrollably as a small probe was used on me. Is this also because of prostate stimulation? Are these the types of sensations the Aneros will give me? If someone asked me what prostate stimulation felt like I'm not sure I could answer them. Could some of you describe what sensations you feel during prostate stimulation. I'm sure it's different for everyone.

I would also like to hear from people who were already somewhat advanced in anal stimulation when they first experienced the Aneros. Was the Aneros a completely new experience for you? Did it take long to get control over it? How does it compared to other anal / prostate stimulation you had before you experienced the Aneros?