Well as one one of the original Wiikey owners ( I installed one myself shortly after they came out ) I burnt and played most of my games off the Disc for years.............never had a problem, every game run just fine, I had to update once or twice I believe when Super Mario Galaxy came out, but every single game I burnt works just fine ( if I only try to compare that to the old days when I was burning Sega DC games with a rate of success of 30%, not to mention that some games would stop to work after a few weeks! ).
Not too long ago I had a spare USB drive and I decided to hook it up with my Wii just out of curiosity, and boy, was I glad I did it !
I'm using the Configurable USB Loader, and everything works nicely and I managed to play everything I threw at it.....Sure I had some problems with GH5 and NSMB, but with the right isos everything works like a charm.
Onestly I can never go back to burn DVDs, unless a particularly difficult to boot game comes around , in which case I'll still be able to play it since my Wii is hard modded too....
I also tried other loaders, but I really like the Configurable USB Loader a lot, and games like Scarface running from the USB drive are finally quite and run smoother then ever !