This, usually xDIt doesn't matter to me, since I can usually whip up an SU within a couple hours.
This, usually xD
But nah. I think reservations is a good thing usually. First come, first shot at a spot. If the GM believes that they want someone other than you for the spot, they'll decline you. Or they should, at least. It's often much more harsh to not allow reservations and have players fighting for a spot. I don't like to make people sad :')
Mixed feelings, really. I guess my preference more or less depends on the number of slots one plans to have available at the start of an RP. If there are good number of slots, like say... eight or more, I kinda see where a reservation is more warranted. If it's a smaller RP, like six or so, then I kinda think the SUs are better in a more "just post a sign-up and there will be judging a few days later" sort of thinking.