Seeing as it's Nintendo and anywhere a buck can be saved, a buck will be saved... I guess it's safe to assume that the bus still maxes out at UHS-I (Class 10) speeds and there's no point in buying anything faster than the ~$20 256GB Silicon Power Micro SDXC card on Amazon? About to put in an order for a new card and a screen protector that fits the OLED so I have everything ready on 10/8.
New dock is kind of interesting. It looks quite a bit nicer than the old one, but I'm curious whether it will dissipate heat any better or not scratch up the screen. The ethernet port essentially replacing the "internal" USB port makes me suspect they wired it up via the old USB 2.0 connection and it will end up not being any faster than the USB ethernet dongle I'm already using on my current Switch. Sure, it's a lot faster than the abysmal Switch wifi speed, but it's nowhere close to the actual speed of my cable when I need to download a game or patch.