Well my own blood doesn't gross me out at all, so yeah, I'd try it and go head-to-head with some scrub if you payed me enough. Blood is just messy fluid, like oil in a car to me. I'm bothered by plenty else, but not of a potential slipping hazard.
That said though, this doesn't seem like a very effective way to "up the ante." Having blood drain out of you through a needle doesn't hurt, like at all, unless you jostle the needle around somehow like a goof, so there'd be a lack of direct negative feedback. If I were to get hit in the game, I wouldn't notice a difference if I didn't look over to the side at my blood draining. And then you can't possibly lose enough to pass out or even get dizzy because of the blood nanny you'd have watching you. This is just for shock value and blood donation. I bet if you do too well at the game, you'd probably be pressured to give them a usable amount, so it's just a straight-up blood donation, you might as well go into a blood center and play a handheld.
That said though, this doesn't seem like a very effective way to "up the ante." Having blood drain out of you through a needle doesn't hurt, like at all, unless you jostle the needle around somehow like a goof, so there'd be a lack of direct negative feedback. If I were to get hit in the game, I wouldn't notice a difference if I didn't look over to the side at my blood draining. And then you can't possibly lose enough to pass out or even get dizzy because of the blood nanny you'd have watching you. This is just for shock value and blood donation. I bet if you do too well at the game, you'd probably be pressured to give them a usable amount, so it's just a straight-up blood donation, you might as well go into a blood center and play a handheld.