I purchased it brand new a year ago (leftover at a local camera store), put it in operation straight with K7 glossy, printed around 50 A4 photos (with an additional pass of GO for each) in a couple of weeks, then cleaned it, installed PiezoFlush carts, got a perfect nozzle check, and stored it in its original plastic bag inside the original box (which is not air sealed, a detail I could have improved).
Sorry for not being clear at the beginning. We cannot tell from my experience whether the recovery after the hibernation is easy or difficult, because I committed at least three mistakes that caused the introduction of air in the print head:
1 - A year ago, I had the printer already stored with the vent plugs of the PiezoFlush carts removed, then after discussing with you about hibernation, you told me that the only thing I made different from your case was not putting back the vent plugs; I though it was an important detail, so after a week or so I unpacked the printer, but in my case, since I haven't removed the cart cover (my understanding is that you have to break the hinge to do so), I had to turn on the printer, put it in cart changing mode, open the cover, put the vent plugs, close the cover, and then press again the cart changing button. This triggered an automatic head cleaning; probably if you press the cart change button, don't remove any carts, and then press it again, the printer doesn't perform an automatic head cleaning, but if the printer has been disconnected for a while, it does even without removing the carts.
2 - A couple of days ago, when putting the printer back in operation, I forgot about the vent plugs. I ran probably a couple of nozzle checks and cleanings before remembering about them.
3 - A couple of days ago, after having removed the vent plugs and run several nozzle check and cleanings, which recovered perfectly all channels but two, seeing that I had Y and Or with about 10 missing lines each and no sign of improvement, I though of doing a PiezoFlush application with the small printer cleaning kit, but not remembering the correct advice of not emptying completely the syringe, I emptied it completely and then pulled, which created a lot of bubbles, and made the nozzle check of those two channels even worse (though at all different locations, hence I was sure I didn't have a clog).
All the next steps have been attempts to remove air from those two channels.
So, knowing all this, we can probably conclude that PiezoFlush hibernation doesn't produce clogs, though we cannot tell anything about whether the recovery, if one doesn't make any mistakes, is straightforward. This is why I was asking for somebody else's experience.