I too was trying to decide between bx 42 vs. 62 last fall for my NH Boomer 3045 with 37 HP @ PTO. Was also concerned about being underpowered for bx 62, but others here recommended 62 and forked over the extra 800 bucks and got the bigger one.
No regrets 8 months later. Tractor handles easily up to 6" logs; even got greedy and went bigger. Popped the shear pin with notched 8 incher but now I know its limit. Pin replacement a piece of cake by the way.
Best thing is the larger hopper which allows insertion of multiple branches which requires less trimming.
Definitely my favorite man machine; just be careful when using it and where appropriate safety gear including face shield/helmet. It is also an excellent ballast when returning from the woods with a loader full of rounds.
Would send pics but on the wrong computer. Sorry