Yes, I think the tingling sensation is like the tens unit and as far as the SMS being permanent....If you consider this, you are required to have a trial done first to see if it works. If it does and you decide to have the surgery, the leads are then implanted. They can be taken out at a later date but with any surgery, there are always risks so you really need to be sure this is what you want to do.

The nice thing about the SMS implant is that you have the ability to turn it on and off. I have found that after I turn it off I still feel a little tingling afterwards. I was even told that some people can have it at such a low frequency that they don't even feel the tingling and it still will interrupt the pain signal to the brain. I personally have not experienced that so I feel the tingling.

As to your other question about the coverage from lumbar to cervical. I believe it can cover those areas. Even though I have chronic pain throughout my entire body, I was not a canidate for it to cover both areas.
I would check with your doctor/neurosurgeon as to what is available for your specific needs because I am no way qualified, other than to tell you thru my experiences.

Hope that helps a little. Good luck!