I use the g4m to gain some points when I run out,( b-29s are not indestructible ) a good run with the 4 bomb load will net you 40 or 50 perks in late war on a good day with 4 city centers,, use the formation, Remember that in the hanger is a perk point multiplier box, if that number is high, you can make more points,, if that number is low, not so much,,
I'd be happy to help you on bombing and or flying them in the training arena if you would like,, the b-29 doesn't cost anything there so you can practice take offs and landings with the formation without fear of losing a bunch of perks
I fly the b-29 in the main arena but unless you fly the strat areas, you'll never see me,, I'm at 30k plus from the time I leave freindly territory till I get back,, they cost to much to risk them at low alt in enemy territory
One other thing,, when the perk multiplier is high,, the cost of stuff like the b-29 is lower
Anyway let me know if you'd like some pointers,, just PM me if you like