The 873 was Bobcat's first attempt at a large frame vertical-lift machine, like a larger version of the 773. When it was realized that the booms were not as robust as an 863's, we were told that the 873 was more of a "lift and carry" machine and the 863 was the digger. That was the party line when I was an employee of a Bobcat dealership. In retrospect, that seems like a pretty cheesy sales pitch. The 873 went through some Boom updates, both field and factory, before the new G-series came out with a redesigned boom and frame. They initially stayed with the oil-cooled Deutz, which not a bad engine, but it's kind of a heat-prone application, IMO.
Still it was pretty popular when it came out, but the newer ones make it look like junk, so compared to those, no, you're not missing anything......=).
That technology is already over a decade old, now, I believe.