In the end Me410 would most probably see more use overall in the LWMA. As it has been discussed, B-29 takes ages to climb to safe altitudes. It must be heavily perked regardless, which makes it rather compulsary to climb to high altitudes in order to fly the perks home and that takes more time than most are willing to spend just climbing. At low altitudes it will be significantly slower and due to it's status and hefty perk cost, it will be like flypaper to fighters.
Once it's up there at 25-30k, it will be very hard to intercept/shoot down but very few will have the patience to take it up there regurlarly. On top of the low use, it will take a lot more time to model art-wise than a Me410, which will also be used more. So in this light, Me410 will offer more bang for the buck.