About a year ago, we tripled the size of our market gardens. We raise organic vegetables, almost 30 varieties. I began with a Kubota BX, a tractor quite similar to your own NH. To take on the expansion, I needed ground clearance, not necessarily a bunch more horsepower. Herb farming is a specialized form of market gardening, so I understand a bit of what you are going through.
I loved my BX, but a subcut simply wasn't able to handle the row work of market gardening, with its very limited ground clearance. I studied a lot and decided upon a Kubota B2320 with its awesome ground clearance. One of the best moves I've ever made. It is virtually as nimble in the gardens as a BX but so much more capable.
A huge, lumbering, heavy tractor simply isn't suited for this kind of specialized farming. More is not more!!! I'd encourage you to think through the specifics tasks and specific implements you'll be using in this 3 acre project. I also wish you the very best in getting the right machine for the future. Best regards,