Yeah, I'd sort of like a backhoe, even though I'd use it only once or twice a year. The reality is that much of the trenching I do I couldn't get the tractor to anyway.
Not here with all this limestone/bedrock, guess thats why this house is on a slab with no basement? A backhoe would be great for a lot of trenching needed around this house, need to level and dig for a new porch and drainage.
Better get a DEDICATED backhoe for the work you describe.
You definitely wouldn't want an add-on (3ph) backhoe. Digging limestone will work it pretty hard. The subframe attached model will do better, perhaps with a ripper on it rather than a bucket. And work slow. But ultimately @fried1765 is right, a mini-ex will do that kind of work way better.
I wont be digging bedrock, but there is a lot of busted rock buried in the soil around the house, can be dug with a shovel just a PITA.... even if I had some sort of a digging hook to just drag behind the tractor would work, just a backhow would be nice to have, not a deal breaker.
