I expect to have the Canon 5DS R on Tuesday June 16.
For background information on the Canon EOS 5DS / 5DS R, see this page and others linked from it:
Accessories for Canon 5DS / Canon 5DS R
Below are tems well suited for working with the Canon 5DS R in various contexts (most apply for the same reasons to Nikon D810 and Sony A7R II):
- Canon LP-E6N Lithium-Ion Battery Pack (bi-way compatible with the Canon LP-E6 used by the Canon EOS 5D Mark III)*.
- Lexar 2000X SDXC, a very fast card (see review of Lexar 2000X SDXC 64GB).
- Lexar 128GB 1066X Compact Flash (see review of Lexar 128GB 1066X Compact Flash card)
- Dual-slot card reader.
- OWC 1TB USB3 SSD (or 480GB) for in-the-field backups or site shoots (great for desktops too as a silent and fast bus-powered accessory).
- OWC Thunderbay 4 20TB or similar for storage and of those big files, with various flavors of RAID and fault tolerance as options.
- The blazingly fast 2015 Apple MacBook Pro Retina (see review of 2015 Apple MacBook Pro Retina).
* Chuck Westfall of Canon USA response to my question on batteries:
The EOS 5DS and 5DS R are compatible with both the LP-E6 and LP-E6N battery packs. The only operational difference is the shooting capacity, which is very slightly in favor of the LP-E6N (1865 mAH vs. 1800 mAH).
The LP-E6N is rated at 700 exposures per charge at room temperature, the figures for LP-E6 will be slightly lower.
The main reason we changed to the LP-E6N has to do with recent changes in Japanese regulations for lithium-ion battery packs.
The original LC-E6 charger is fully compatible with both the LP-E6 and the LP-E6N. Let me know if there are any other questions!