If you choose voluntary departure, how long before you can reenter the United States?

It is my understanding that if you are say subject to the 3/10 year ban and you take voluntary departure you are still subject to the same ban. The only difference being, is that you do not have the stigma of being "removed", You should exhaust all other avenues before taking voluntary departure and that you can only do if it is offered to you.

Voluntary departure is supposed to be less harsh in the long run, as they tack on even more consequences to those who are "removed". I think that you have a better shot at getting a green card one day if you depart voluntarily, rather than being deported. I can't remember it right off the top of my head right now, but there may be something about a 5-year ban on re-entry with the voluntary departure, verses a 10-year ban with deportation. Don't quote me on this.
IF you are eligible for voluntary departure (not everyone is), and you are granted such before or during the removal proceedings, and are able to pay for your own transportation out of the country, you may (they say) choose where you want to be deported to. You may also be granted 120 days to remain in the US to sort out your affairs before you go. If you wait until the end of your removal proceedings, are then granted voluntary departure (again, if you can prove that you can pay for it), you will only be granted 60 days in the US, and you may not choose where you want to be deported to.
If you acquired 180-364 days in this country illegally - for whatever reason - you will face a three-year ban on re-entry. If you acquired 365+ days in this country illegally, you automatically face a ten year ban. Waivers are virtually impossible to obtain. Especially without a lawyer.

I hope this helps.

This is a question rather than a reply:

1. Has anyone heard of persons being turned back/denied re-entry because they don't have a re-entry permit? The green card holder has been out of the country for a little more than a year.

2. If he "voluntarily" gives up permanent residency, does the 3 year ban apply? Or can he be re-petitioned again or apply for a tourist visa instead?

1. It's certainly possible. The INS officer might assume that he gave up his permanent residency unless he applied for the re-entry permit in advance.

2. How can he be subject to 3-year ban if he can't even enter the country? I think he can apply to re-instate his status.. but i am not sure.