I have a landpride 54” for my B2650 it is exactly the width of the rear tires. I went with 54” for a few reasons keeping my footprint small for woods work and also storage purposes. So far I haven’t wished I had a 60. Definitely no bigger than 60” I’ve had my 54” full of wet gravel and it will stop it, hard packed dirt, and clay have also stopped me. 54” May take a touch longer for some tasks but for me I’m not trying to make money with my rig. Just make things around the house looks nicer and a little easier to do!
I do think you’ll find the general consensus to be a 60”
Weight is your friend; if there's a choice between similar boxes, pick the heavier.
Also, the wider it is, the easier it will be to level large areas. The narrower it is, the better it will dig, if you're cutting a road into a bank or such.
What they said, if it ill handle the 60", I'd get it. I have an HR3584 on my 5740 and like it sticking out a bit on both sides, easier to get right up against something and not get the tractor into something.
It should handle the 60" with ease. I had a 60" King Kutter that I used behind my B2400, and it handled it just fine. If you are using the scarifiers, high range will be out of the question on the B2650, but you wont have a problem filling the box and using it! I have only used it for light grading and leveling behind my 2650, and it barely knows its back there.
I just purchased the 60" from everything attachments. It appears to be a very well made unit and they actually painted it orange for me for a slight fee. Honestly, it's just been too wet here to use it but from a build perspective, it appears to be quite heavy duty. The cost was substantially lower than LP (especially when considering the construction).