natalie:

I was under the impression that you could confirm a flight in XY or XC and then be on standby for a higher class if you go ahead and ticket.

For example, if you wanted to fly in XF (award First) from DEN-SFO-NRT-BKK, and NRT-BKK didn't have any XF seats, but did have XC seats, you could ticket the trip and 120K miles would be lifted from your MP account. The NRT-BKK flights would be confirmed in XC (or even XY) and you would be on the standby list for XF.

But I think you have to actually ticket the trip to be on standby for a higher class of service. And if that segment never cleared for the higher class for a particular segment, you wouldn't get the miles back (assuming you did ride in XF, say SFO-NRT).