From what I know: (and this is for state corps)
The cash raised from sold shares goes to the owner - the country.
Running of the corp remains the same as long as you have a controlling number of shares.
If you retain 51% or over of the shares then no one could nick the corp unless they buy it outright.
You cant nationalise public corps, (ones you have IPOed).
My view is it is pointless IPOing nowadays as you have very little say in who buys the shares. It used to be very advantageous when you could could state corps to CEO corps. To do this nowadays involves a lot of manipulating of P/E and MV so no IFs buy the shares.
What you are doing basically is selling a part of the monthly profit for a one off lump sum. So it's how you want to be. I think I would IPO while you can but only sell a very small amount of shares, like less than 5%. You dont know when the corp might be IPO-able again. And that way you still have complete control and 95%+ of profit coming to you.
Last thing, if you can sell shares down to less than 25% ownership then you get a truly public which does change things, but that means no one else must own greater than 25%, excepting IFs.
Remember, IFs can NEVER control a corp, even if they own 100% of the shares.
There's my take on it sbroccoli, you may be well advised to listen to others comments too.