I look at it this way: With the cost difference (up front + energy), it is very easy to justify having a spare on hand.
	Beyond the obvious, you can also swap the spare in every month. That allows you to take your time and clean it right.
	I plan to have 3 x QO4K in my system, plus one spare.
	Every month, I will rotate in the spare, so each pump gets cleaned every 3 months.
	For the spare, you let it dry out, then soak in a bit of tap water + vinegar, rinse, etc.
	Since you have a month to get it done, instead of a big rush while your filter is idle, you end up doing it, instead of procrastinating.
	
	FYI: I tend to do the same with powerheads. I used to on my current system, until I switched to the rather expensive Vortechs.