Upload & Sell: Off
What kind of event?
Most ppl will push for dye-sub, as they are most convenient for 'events' - that is, load a roll of paper and 'ink' and they'll give you 250+ prints without intervention. They're fast also, spitting out 5x7s in about 15 seconds or so.
Then there is me, but I only do events that range from 1000 to 15,000 competitors per day. I use inkjets. By pooling multiple inkjets together, I can match or beat the speed of a dyesub and have built in redundancy - all for a fraction of the cost of a single dye sub. The catch: you have to feed them more often.... paper and ink.
Also with inkjets, you can get supplies at nearly ANY office store in the country - or even a new printer if you need. With dyesub, you had better order all the supplies you think you might need, because there are very few stores carrying supplies... usually internet order.
Finally, inkjets offer a wide variety of paper choices. Not that you would present that to your customers, but at least you have the choice to give them a better looking print (glossy, matte, luster and anything in between) than with dye-sub (only one type available) And ask anybody who has ever seen a dye sub print compared to an inkjet: side by side - they'll tell you that the inkjet has more depth and looks better.