If anyone here has any mixed-metal reservations, keep a eagle eye on those reservations. I've now had two instances of CO/UA dropping segments when mixed metal schedule changes have occured. I've documented one in the schedule change thread, basically BOS-MCO on CO then MCO-BOS on UA. In that case the MCO-ORD changed from UA metal to CO metal and it was dropped off of my itinerary. After a lengthy call I was able to resolve. Today, I noticed that my award ticket to YYT had a schedule change. All that changed was the "UA" metal flight number from YYT-EWR. (A mixed airline ticket outbound on AC in first class, then return to BOS via UAex+colgan on the return). This resulted in having two YYT-EWR segments posted and no more Colgan EWR-BOS. After another call, this was fixed, however, they dumped my seat assignments on the UA flight. So I called UA to confirm, and while this YYT-EWR is a UA metal flight, it is controlled by CO. And I "think" I got 3C on that flight in E+ (that's what they told me, however, the seat map doesn't reflect that seat so who knows) and I have a "---" for the seat assignment. While all the agents have been very helpful fixing this up, it has been very frustrating. For people that are not eagle eyed like myself they will go to the airport and perhaps then notice that a flight segment is missing. That is not good. I hope they resolve these issues soon.