Roughly every six months the user is advised on the LCD to perform an all-channel deep cleaning from the Admin panel. It is not mandatory, but advised to maintain the health of the print head. If this sounds like the six-monthly call from the dentist to get your teeth cleaned, the analogy isn't too bad. Neither is mandatory and both are probably good for your health or your printer's health, except the cost of the Epson procedure is typically less than that at the dentist, at least here in Toronto. It uses about 70ml, so roughly CAD 70.
The ink swap uses probably about $5 worth of ink.
If the P5000 has been left unused for a week or more, the printer will do an auto-clean that is beyond user control. This auto-clean, one can tell from listening to it and timing it, does not consume much ink (again, I fault both Canon and Epson for their secrecy over the use of ink for maintenance). Apart from that, the user maintains complete control over the extent of cleaning a P5000, which is a feature I like. I accept all these pigment-based printers consume a fair bit of ink for maintenance, but I like to be able to control it myself and know what's going on.
Hard to say which model consumes more or less ink for maintenance without keeping careful records and similar usage patterns for both, involving the weight of the maintenance tanks at timed intervals under similar conditions. This is very hard for anyone to do, and as such makes these comparisons hazardous. At the same time, for me, this would be a low-priority variable for making a decision on which printer to buy. I could go into that, but I have before elsewhere and it would off-topic here.