I have a BX2200 that does an excellent job of mowing with the MMM and mulch kit. If I were you, I would get the BX24 with MMM. The MMM cuts well and comes on and off quickly after a little practice.
I would just use the backhoe for the holes. For really difficult ground, you can take the bucket off and use a Bro-Tek ripper on the end of the arm. If you particularly need cylindrical holes for some special reason, you could excavate with backhoe, backfill and compact, then bore your hole with an inexpensive PHD. Since you're in NH, you could drive over to N. H. Northern Tool and Supply and pick up a Greene PHD which is only about $400 and another $90 to $140 for auger, depending on diameter. Granted that's a bit more work, but if money does matter, this is an option that could save you a lot.