I couldn't live without mine. I personally prefer Really Right Stuff, though I wouldn't hesitate to buy a Kirk bracket either. I got mine off ebay and saved about $80 over a new one. They seem indestructible so I wouldn't hesitate to buy used if you can find the model for your camera.
I use mine in conjunction with an aluminum bogen tripod that I've had for ages and an older kirk ball head. I've been looking to upgrade to something a bit lighter though, and have been eyeing the Gitzo GT3531S tripod with the RRS BH-55 ball head. Acratech makes some pretty cool and innovative heads as well. There's also always the arca cube to lust over but I doubt I'd ever be able to justify that...
I have had a RRS L-plate on several bodies over the past 7-8 years. These have used mainly with a screw clamp from Arca-Swiss mounted on a B1 ballhead and Gitzo legs. I also have Kirk tripod collars for a couple of lenses along with a RRS lens foot for another lens. I've had the tripod for 8 years or so. Everything has been rock solid.