If you're going to use kiosks, might as well plug a 2.5" external HDD into them because flash write speeds are pitiful, you'll be there for hours with flash. With external HDD's it will still take a good half hour if not more. Sounds like an over elaborate way to avoid optical media, which would likely to be cheaper. Just make the games available on disc and dd, let the user choose how they want it.
http://www.everythingusb.com/super-talent-usb-3.0-raiddrive-17951.html
200MB/s or 320MB/s with the driver they talk about
10 gig game at 200MB/s is 51.2 seconds . 10 gig game at 320MB/s is 32 seconds. Double it fora 20 gig game and your at 102.4 seconds or 64 seconds.
Not out of the realm of being viable.
THe problem is if you make the game avalible on disc , our going to loose out on the advantages of hardrive speeds both transfer and seek time because the game still ahs to work on disc.