I have both models and use the 4200 regularily for hunting on my ML while my 3200's are used less or in back up rifle rolls. To me it is clearer and brighter due to the enhanced coatings but only you can decide if it really worth it! I do notice some gain in low light but the 3200's I can't recall caused any problem under legal hours either. It was more I had the scope and found I really liked it on my ML setup, so therefore it has stayed and is used a fair bit in that application.

Either are decent scopes but I would suggest going to a local shop to compare them outside in low light situations to decide for yourself if 150 is better spent on glass or something else. You also might find others in the 4200 price range that you like better and feel offer you more, you just never know!

Best of luck