I really just wanted to address this. The last person to hold the belt longer than The Miz was Triple H back in 08. If he loses at Mania, it'll will be the longest WWE Championship reign in almost 3 years. I think this speaks volumes about the current state of the WWE. No one gets long reigns anymore, so by current standards, The Miz's reign is an amazing accomplishment.
And I can say Edge's 11 Heavyweight Championship reigns are so amazing that he deserves to go over the likes of Steve Austin, the Undertaker and Hulk Hogan - but truly smart individuals will see directly through
that (well, now

) and understand that even though he has more reigns as Champion - it's what he did with them, that was less attractive.
That same understanding works in place here. Yes, Miz will have been the longest reigning Champion in years, as it were.. but who has he beaten without massive amounts of help? Infact, Edge at least defeated Flair in a TLC match without help - Miz has yet to prove he can even beat Lawler without the slightest interference from Riley. Miz was getting squashed by Cena before this year, and even with Riley - I doubt much will change.
Miz has only defeated Orton in a warped sense of the term. He's retained via countouts, or DQs. Maybe he's won because Riley pulled Miz through a broken table that he broke himself, to win in typical heel fashion.
He only
JUST defeated an aged Jerry Lawler, and even then he needed Riley to interfere 3 times before he was kicked out - and then, Miz struggled a lot before finally winning. Christian is not an aged announcer who's prime was 20 years prior.
Miz can hold the title for the next 2 years. If that reign is similar to the past 2 months, it won't make him worth a damn as a Champion; because he won't have done anything to deserve the acknowledgement. And the same was considered for a lot of Edge's reigns, unfortunately.
On a sidenote, I find it hilarious that someone who supported EDGE in the past few years is bashing Miz for not defending his title cleanly. Until his recent face turn, Edge never won clean. Miz is doing this by the book of heel, and his doing an excellent job. The last thing you can call his reign is transitional.
1.) Yes, he is doing this as a typical heel and he's making it work. That's why he is carrying the title into Mania to likely get squashed and put over the face.
2.) Even as a die-hard Edge fan, I never once defended his 1st title reign because he was every bit of a "transitional" Champion. He was handed the title for 3 weeks to test run how he'd handle it. Obviously, 10 more reigns later, the Company felt he was worthy of it. Miz has 1.. Mania may be his final stop as Champion, or maybe - just maybe - he'll retain and shock everyone, myself included. The bigger question is, once he loses the title.. will he ever get it back? I'd be more willing to bet Miz will be similar to Swagger and fall back to the mid-card ranks than he'd ever be like Edge and win the belt even 1 more time, much less 10.
As it relates to this match, Miz can use all the heel tactics he wants. Christian is more considered to be like Orton, or Cena, in this situation than he would be like a guy such as Lawler. And thus far, unless a table is involved - Miz has lost more to those other two, than he's won via pinfall.
Christian should win this one quite easily.