I am considering that move as well (owning Us & Ks). But i will do that only if i should be out of cash at that moment because i think overall the prefs will be the better performers.
In a perfect world the first offer will be preferreds at close to full face value, 80 - 90% and commons nothing. Then we all sell preferreds and buy commons. Then a second offer comes for commons and we all make out big agan, lol...