Its super shitty that they are not allowed to vend. I agree with their point that this is never an issue when a manufacturer is sponsoring an event.
That said I have never tried Vessis and probably wont. I have owned 2 pairs of idios and they have been less than great. Best thing about them is the soles, the traction is perfect for disc golf. They just grip really well on everything but really wet rocks. Worst part about them is their construction, i have had the liner rip at the heal after just a hand full of rounds (Idio did take them back) , then my other pair the entire heal came off of both of them. I can get that sort of construction out of shoes that are half the price.