is it dangerous to launch wii games through usb loader gx in 480p while having your wii settings in 480i?
You can run into potential video issues forcing your Wii to output the video into a format that it cannot support natively when you don't have the right equipment. HOWEVER, in the i/p department, this is fairly minimal the worst case is that you're practically cutting your working framerate in half. I recommend keeping the default video settings for USB Loader GX to the global default (which is whatever setting is noted in the Wii Menu settings) to minimize potential issues only tweak the video settings on a per-title basis as needed.