My experience is a Cat 308 shovel is equivalent to a Case 590sm, in terms of digging anyways.
Backfilling with a mini ex or back hoe kinda sucks. Precise sure, but slow. Skidsteer or loader if space allows is significantly faster.
As Welder Dave mentioned, the skidsteer and mini ex combo is a good alternative to a backhoe, and that is what we choose to run. Mini is made for digging, skiddy is made for moving and lifting. Our sites are too far apart to run a machine on the road, so we trailer them, but behind our single axle dump I can easily float the mini ex and skidsteer together.
The biggest advantage of a backhoe is the ability to road the machine. If that's not of significant value, I personally wouldn't bother with one. They're a jack of all trades master of none kinda deal. 2 machines is more versatile and generally faster, even if you have to jump back and forth between them as a solo operator. I do it regularly. That said to start out with, buying a mini and making some $$ with it, and then picking up a skiddy later on is a relatively low risk approach, and lets you figure out what you really need.
That's my 2 cents.