I have a bh75A. I think the price is just a tad high. I'd try to get him down another 500 bucks. For what it's worth, my backhoe has been amazing. I have a mechanical thumb on it, and have built a 6 foot high x 100 foot long rock retaining wall with it. I've moved rocks that are so freakin' big, I have to shimmy them into place by lifting one corner at a time. I've dug oak stumps from trees 12+ inches in diameter. It is very capable, and very durable. It will easily overpower the tractor. The tractor is so light you can just drag yourself around if you don't work smart. It's not a full size machine, but if you work smart, there is almost no limit to what you can do with it.
Okay, all that being said, dollar for dollar, I would consider the curved boom 77 versus my straight boom 75. I don't buy into the curved boom better for digging argument - not with such a small hoe. Maybe better for loading a pickup truck. The reason I like the 77 better is because the boom cylinder is out in the open. The boom cylinder on the 75 is inside the boom. I had to replace a hose that had chafed, and I had to drive out the pins and remove the whole cylinder from the boom to get at the hose. Royal pain in the neck. I thought it all out ahead of time, and it wasn't particularly hard, but it would be a lot easier to just replace the hose and be done with it. Plus, if there were a problem with a hose inside the boom, you wouldn't see it until it was too late. For that reason alone, I think I would buy the 77.