I've been reading this thread since it started and have been baffled by all of the experiences I've read. I have had OH twice now, and I remember the vent both times.
I do have to say that the first time was definitely the worst, because I was unprepared. I had very little knowledge at that time. When I woke up with my hands tied and had no way of communicating with anyone, it was very frustrating. And I often found myself fighting against the vent, just as Kevin said (though I didn't end up with the same complications, thank goodness). I would go in and out of consciousness, and every time I became aware of the vent I would feel like I was choking. I had to force myself to relax. I remember very vividly when they finally took the tube out. It was not a pleasant experience, by any means (some day I'll have to relate the whole story, it might even make you laugh), but I was very greatful to be free. One word of caution, though. When they finally let you have a sip to drink, be sure you actually SIP. They brought me some apple juice and I was SO thirsty that I sucked down half the container before they could get the straw out of my mouth. I regretted it after the third or fourth gulp, because it all came back up!
My second experience with the vent tube is quite different. That time I was prepared for what was to happen, and I think I was also better sedated. I knew that the only way I was going to get rid of the d**n thing was to start breathing on my own. So every time I became conscious I would tell myself (since I couldn't talk to anyone else) to breathe. I would take slow, steady breaths WITH the ventilator, and it was a much easier experience. I do not have as vivid a memory of the removal of the vent tube that time, and I'm greatful. Though, I do enjoy telling the first story to heart-healthy friends because it freaks them out.
(That story and the time I woke up in pacemaker surgery get the BEST reactions)
My advice to you is to talk to your surgeon about keeping you sedated, but to also be sure to keep calm if you do wake up with the vent tube in. Remember to work WITH the ventilator, not against it. I, along with many here, know from experience.