Can you use SDXC cards with Raspberry Pi B+? Indeed, you can. Now, here’s the lowdown on the situation. SDHC and SDXC apparently only differ by the recommended filesystem used to format the card. So, there is no hardware reason why SDXC cards wouldn’t work with the Raspberry Pi B+.
However, the boot firmware of Raspberry Pi B+ only works with the FAT32 filesystem. So, this means you have a little bit of a more complicated time setting up the install image, but that’s it. Make sure there is a FAT32 partition on your SDXC card when copying boot files for NOOBS, and NOOBS can handle the rest.
Now, the next step after this is to build SDXC cards without NOOBS, using your own OS image. I have yet to try that out, but the point in hand is that I can buy the hardware without worrying about not being able to use my extended storage.
20180826/DuckDuckGo raspberry pi b+ sdxc
20180826/https://www.reddit.com/r/raspberry_pi/comments/1yutlz/can_we_use_the_new_sandisk_ultra_128gb_with_the/
20180826/DuckDuckGo raspberry pi supported sd cards
Bingo! This is the documentation you were looking for.
20180826/https://www.raspberrypi.org/documentation/installation/sd-cards.md
20180826/https://www.raspberrypi.org/documentation/installation/sdxc_formatting.md