Originally Posted by
AKLifetimeFlyer
My takeaway from this is that using the Price Guarantee isn't going to knock you into a fare class that earns less than 100% EQMs, nor will it disable you from getting a regular complimentary MVP upgrade. Although it will make you go to the back of the line.
Using the Price Guarantee along with an upgrade certificate however can cause some problems it seems.
Yes, it can knock you into a lower fare class with the resulting consequences. See my post #2 above yours where I replied to your original query. I was knocked from a K fare to a V fare and was then unable to apply a GGU. I had to call in and get the agent to re-upfare me back into K and pay the same amount I had just gotten back on the Low Fare Guarantee claim to get me back into an upgradable fare bucket.
So yes, you can get dumped down into a lesser-earning, non-immediate upgradable fare class and, as far as I know, there is no way to tell that before you pull the trigger. You can always still request a complimentary upgrade, of course, putting you at the back of the line, but it can definitely change your fare class. That is why the agent advised me to call in rather than doing it online. Read the post I linked to in #2.