You can buy the game on Steam, and if it doesn't work well, or if you don't like the game, you can get a refund. You need to have played the game under two hours for this to be possible. The launcher of the game counts as play time, mind you.
Note: you can only do this with the Steam version. The version sold directly by Frontier on their site can NOT be refunded for such a reason as "I don't like the game" or "it runs slow." At least I don't think it can. Someone here will probably correct me if I'm wrong.
More info:
http://store.steampowered.com/steam_refunds/
Umm... thanks for all the patronisation, but I bought the merc. pack. I don't need the demo for myself but for a couple of friends who've been sitting on the fence for a while now. I hope for a demo to pull them off that fence, one way or the other.
Besides, what you suggest isn't acceptable, anyway.