I owned a Z3100 for years. I did replace several heads (especially the red channel multiple timesl for some reason) over that time frame but individually, they aren't that expensive (two channels per head if I remember correctly). I have since owned Canon's ipf8300 and ipf8400. I can honestly say I don't see any significant difference in head clogs, which are rare, especially with the Canons. My printers goes unused for periods of time as well.
Everyone talks about how the Z's sip ink, and they do. But Canon ink is significantly less expensive per ml, especially if you buy the larger tanks. Canon likely has the advantage here from a cost perspective.
If I were to replace my current printer, I would focus on other features besides clogging because it really has become an insignificant issue between these manufacturers. Just my two cents.
Miles