I have nothing to gripe about.
I've got a $200 4-channel recorder that performs much better than any $200 4-channel recorder has any business to.
For more than 6 months I've been using it almost weekly to record 4-channels and have used it as a straight 2-channel recorder (with the 2-channel back up tracks enabled, so I guess even those instances are still using all 4 channels) probably half a dozen times on top of that and fortunately I've never had any negative issues. I'm recording everything at 24/48.
I'm using a Sandisk Ultra Plus 64gb Microsdxc Class 10 Uhs-1 Memory Card (
http://www.amazon.com/gp/product/B00NPJBYD0?psc=1&redirect=true&ref_=oh_aui_detailpage_o00_s00) and have installed all of the firmware updates when they've become available.
I formatted the card in the recorder several times the only way possible via the older firmware version and did the new full format that's available with the latest version before I last used it. (Even the full format option only took a minute or so to complete).
I never put any of that into your spread sheet, but there you have it. I may be in the minority but so far I've had nothing but good luck with my DR-70D.