The Lancaster has pretty weak defenses, and is pretty slow, this is not the case with the B-29. Everything I see, points to the B-29 being an overly abused monster bomber in the MA if introduced. The only scenarios I foresee playing out in the MA are ones where it is running at maximum altitude carpetbombing the hangars of bases where good furballs are happening, like the Lancaster is presently.
How many guys in this game actually have the patience to up heavy bombers and climb them up to 30,000' where they are basically safe, or comparatively safe? Very few and almost all of those are either bomber squadron guys flying their once weekly formation run or the score guys flying one of their 10 a month bomber runs to keep their ranks up.
95% of guys who upp bombers will never climb a B-29 that high. They dont have the patience for it and "most" have no interest in bombing strats anyways. Nobody is going to do it to hangar bang. Hangar bangers climb to 8,000' and come in 2s or 3s. You can only line up so many hangars in a pass anyways and they are only down for 15 mins to begin with. Nobody is going to risk perks to take B-29s hangar banging at 6,000' of ALT. Why would you when you can carpet bomb with disposable Lancs that cost you nothing?
And nobody is going to upp 29s to down CVs either. First off why dive bomb 29s to kill CVs when you can use Lancs, 24s, 17s, and JUs, which cost you nothing and leave the CV just as dead. And certainly nobody is going to climb to 30,000' to kill a CV because not only would that CV be killed by the time you reached 20,000' but so would, probably, the 3 CVs that spawned after the one you upped 29s to kill in the first place.
So the only time you'd really see 29s is when they are bombing strats. And even then only the very few strat runners, or bomber squadrons, would bother upping them. I doubt even the rank guys would use 29s cause they could use other bombers just as easily and would be risking less. Fly a B-29 under 20k and it will be killable just like any other bomber. If perked at 100 a plane, or 150, even guys with a lot of bomber perks will only take so many hits with them.
This entire fantasy that the "sky would be red with 29s" is just that, "fantasy".