I burned through a lot of heads when I was using Triangle ink. 1-2 a year. Now I'm on solaris and I haven't changed a head in years. However. My yellow is getting old, and has a scratch in it. The head still works, but my printing suffers at times.
If the head was a 100 dollars, I'd would have replaced it a year ago. The head is not a thousand dollars bad at this point.
I'm tech savvy and can do all my own printer maintenance on my Rolands. My father in law has replaced transistors on the head boards, traced all kinds of electrical component problems. I love this about a Roland. I can fix a 1600 dollar board with a 7 dollar part. You won't have that luck with an HP.
I'm keeping my rolands, but adding a latex as well. I think the operating cost is the same between the two.
I want no-odor and instant dry.