Tyrannis,
We've debunked all of your arguments.
The B-29 will climb markedly better than you state, being 28,314lbs lighter at 50% fuel than at 100%. You could even take 25% at times and be ok.
The B-29 has as good or better forward firepower than the B-17G does, depending on the angle the fighter attacks from. It has a much superior M2 20mm cannon (Hispano Mk II) in the tail, along with two .50s as compared to the G4M1's Type 99 Model 1 cannon, though I believe the G4M1 has significantly more cannon ammo.
A formation of B-29s will carry 60,000lbs of ordnance at max, noticeably more than the much slower, much more vulnerable Lancaster's 42,000lbs in a formation.
The B-29 will have a top speed of 355-360mph, faster than any bomber in the game other than the unarmed Mosquito Mk XVI and quirky Ar234, both perked.
It is likely, though not known yet, that the B-29 will be the most durable aircraft in AH, ever. Even monsters like the H8K2, if ever added, would not be as durable.
If it were not perked, as you argue, you would rarely see any bomber other than B-29s unless ENY limits blocked them. There would be no reason to ever fly a B-17G, B-24J or Lancaster, period. Will the B-29 be vulnerable? Yes, more so than the Ar234 or Mosquito Mk XVI, both perked, but less so than any other bomber. The trick HTC has it to find an appropriate perk value to balance its massive war load, performance and vulnerability.