Originally Posted by
RealHJ
And you've surely had many, many aircraft substitutions over the years. Just you haven't even noticed it (if seats don't change, most usually don't notice), or it has been a positive for you rather than a negative, so you've conveniently chosen to forget about it. So will be true for anyone who's flown more than a few times.
I've had many MX subs over the years. The vast majority were same equipment subs. In cases where the reason for the sub was not explicitly stated as MX, they have always been a downgrade--- CRJ 200 for 700/900, ERJ 145 for a 170/175, nonlay-flat for a lay-flat, etc. Last minute MX situations I understand but when it is a sub several days in advance it is much more likely part of their bait-and-switch scheme.