I'm thinking about getting that self-hosting Wifi SD card thing with a microSD card so I can use loadiine without having to connect to the internet. What kind of speeds should I be looking for in a microSD so that games don't lag or anything with loadiine?

 

I think the write speed is more a wiiu problem rather than the sd card you have being at fault as I have tried various brands of sd card on the wiiu and they all write at 136kb/sec

 

Tbh, you are better off doing the USB method, as the games that have long load times boot way faster on USB. You can still use it offline, once you have installed the HB channel via Haxchi, as it does not require any internet connection or sig checks patched to work.

My setup offline is:

USB 500gb drive with WUP installed titles inc, latest updates and DLC and Eshop VC titles.
Haxchi HBL+ Official HBL channel (Dimok) since it has more privilages but requires iosuhax fw.img with sig checks.

SD card with Loadiine for titles not compatible/available via WUP install.