WD10EACS: Huge Load cycle count [ NOT SOLVED] in 4.2.9

To help us understand the consequences (in the absence of official help from WD), here is my data point:

I seem to be an extreme case because I bought early and have hardly ever turned the drives off even though my workload is very low. My load cycle count is now 540,000 - 610,000 (around twice WD's claimed design limit of 300,000) but everything else appears to be OK. I am a little surprised that the drives have very different "Power On Hours" figures for not-so-different load cycle counts, all four drives have been in the same NV+ system powered on for just over a year (about 8500-9500 hours elapsed time), not sure why the drives report a wide range from from 8500 to 5100 power on hours, perhaps the firmware IO is uneven. The lowest load cycle count is on the drive with the highest hours, so it seems to be a problem with idle time that gets better with increased activity.

I have not seen any errors, but I don't know what symptoms to expect other than some unknown probability of total drive failure. Would an empty load cycle (ie park the heads when they are already parked) actually cause much less wear and tear than a normal load cycle?

I'm hoping that the best approach may be to wait until one fails or until I want to upgrade the drives for other reasons (eg in another year or two it may be economical to swap four 2TB or 3TB drives in, or buy a new NAS). The low probability worst case is that one drive totally fails suddenly without SMART warning, and then the RAID recovery from that causes total failure on one or more of the other three, losing the entire contents.

If something happens to my drives I'll post here, and I'll stay subscribed to this thread in case someone else hits a wall first.

Disk 1	Disk 2	Disk 3	Disk 4	SMART Information
				
WDC WD10EACS-00ZJB0	WDC WD10EACS-00ZJB0	WDC WD10EACS-00ZJB0	WDC WD10EACS-00ZJB0	Model:
WD-WCASJ0159784	WD-WCASJ0443907	WD-WCASJ0346720	WD-WCASJ0443775	Serial:
01.01B01	01.01B01	01.01B01	01.01B01	Firmware:

				SMART Attribute 
0	0	0	0	Raw Read Error Rate
0	0	0	0	Spin Up Time
5	5	5	5	Start Stop Count
0	0	0	0	Reallocated Sector Count
0	0	0	0	Seek Error Rate
8495	7302	7403	5118	Power On Hours
0	0	0	0	Spin Retry Count
0	0	0	0	Calibration Retry Count
5	5	5	5	Power Cycle Count
4	4	4	4	Power-Off Retract Count
539897	567165	610837	596694	Load Cycle Count
33	35	35	33	Temperature Celsius
0	0	0	0	Reallocated Event Count
0	0	0	0	Current Pending Sector
0	0	0	0	Offline Uncorrectable
0	0	0	0	UDMA CRC Error Count
0	0	0	0	Multi Zone Error Rate
0	0	0	0	ATA Error Count

				Extended Attribute 
0	0	0	0	Hot-add events
0	0	0	0	Hot-remove events
0	0	0	0	Lp stat events
0	0	0	0	Power glitches
0	0	0	0	Hard disk resets
0	0	0	0	Retries
0	0	0	0	Repaired sectors