Doesn't Gregory Wilson have an entire video that only goes over the DL?http://www.penguinmagic.com/product.php?ID=995
There is the Greg Wilson DVD. For true alternatives to the DL you might check out Dan and Dave's on demand. They have two that are billed as such. Chris Brown's "Venus Trap" and Kotsya Kimlat's(sp) "Undercover switch." The "Venus Trap" is very angly move and will require lots of timing to get down. I think it is a decent top card control but I don't have much use for it as a replacement for a DL. The "Undercover Switch" is pretty bomb proof and deceptive as edited but requires some setup. I actually find it more useful when routined into an effect that does the setup as a by-product. Truth be told neither will replace a DL. You simply need to find a DL that you are comfortable with. I currently use the basic Diving Board DL(Lee Asher) for my performances. It took me three months before I was ready to perform with it and I am just now (almost a year later) getting to the point where I can pull that double without a break. The DL is one of the most common moves in card magic. Find one you like and master it!
Performance tip: DON'T PANIC! I occasionally perform for some of the kids at the school I teach at. One of the kids there has an uncle who is a magician and the kid is kind of a Heckler at heart. He doesn't watch the magic, he wants to bust you! Consequently almost every time he sees me do something with a deck of cards he says, "Two cards!" whether I'm using a double or not. One time I pulled a DL and he chanted his usual taunt. I simply wrist killed the deck and handed him the card. Once he was satisfied, and the other kids were chuckling at him, I replaced the card and went back to work. I still rarely perform for that kid, less now because I'm afraid of getting busted and more because doing magic for people like that is just no fun, but I think you get the point.
Final thought: Many of the of the best card magicians in the world still use the standard DL. They just do it really well! Check out this free Aaron Fisher download. http://www.wizardhq.com/servlet/the-103 ... the/Detail