I would agree that, maybe in 2010, they hadn’t yet hit their peak in the U.K. and Europe and maybe were playing similar venues to DT but they were still a band who were a big deal, who had big label support, had proper music videos, radio airplay and hit singles.
No argument there. But that's the thing, we have to look at things from the standpoint of summer 2010, not what we know came after.
DT were, and remain, a cult band with a fiercely loyal fan base but they always had a certain ceiling which A7X did not have. It definitely felt like a step up for Portnoy from DT to A7X.
I won't argue with you, but there's always the outside chance that DT could break that ceiling. Not likely, but not impossible either, as PMU proved all those years ago.
But regardless, the big reason why MP wanted to make the move was because they were a newer band with younger guys and it was all very exciting to him, as opposed to the old established relationships he had with the DT guys. And to an extent, he has said as much about why he stepped away from DT, even if he didn't specifically talk about wanting to join A7X. I will also reiterate again, this does nothing to prove that MP was wanting to make the move because of the money, or else I'm sure we would have seen him chasing after other big name gigs instead of continuing in the various bands and projects we have seen him in. Perfect example would be Nuno Bettencourt who played with Rhianna. You can be sure Nuno made a lot more cash in that gig than he did with Extreme, and with MP having made a name for himself in the music industry, he could've done something similar if money was the overriding motive.
Even if MP did join Avenged as a full time member - I can't imagine him NOT trying to muscle in on everything and be the frontperson and handle all the decisions just like he did in DT.
I disagree. Consider all the bands he's been in since he left DT. With the exception of SoA where it was stated outright that he and DS would be the decision makers in the band, MP has not been THE decision maker or frontman for any of those bands. And these are all bands that he has been in from the beginning. Plus with them being lower key bands, it would be much easier for him to muscle his way in on everything if he wanted to, yet he has not.
Now consider that A7X is a band that already was established long before he joined them, which he was very well aware of. Perhaps in time he could have become an equal partner in the band, but in no way would he have ever tried to take over everything. The other guys would've never stood for it, and MP would have known that.