</font><font color="blue" class="small">(  Also.. witht he toplink removed.. and the mower still attached to the 2 lower links it WILL NOT travel like a pull mower, as it is still semi-gigidle mounted.  If you make a turn.. the mower swings wide.  On a trailer/drawbar mower.. when yuo turn.. the mower banks..  )</font>
I know we're beating this one to death, so I'll take one last stab to be sure its got no life left.  ... I brought the pull-type argument up, not because the decks would pull the same, but to illustrate that even with only the single connection of the pull type, there's no chance of a major flip-up.  Yes, if the obstruction is off to the side, the deck will likely move to the other side around the object, but if the obstruction is near the center of the deck, such as a large stump that clears the underside of the tractor but not the deck, I doubt the deck will do anything other than ride right up over it, or do some very serious damage.
Also, I think many might think the trailering scenario provided by the three-point, minus the top link, is very nice.  I can do an awful lot of weaving in and out (around trees, poles, etc) with my RFM that I would not be able to do with a trailer-type (draw bar or hitch) type deck.  You kind of get the best of both worlds.  (note: for convenience, I usually mow with my top link connected, but loose enough to let the top link mower connection, flex to the maximum.)