Never heard of the XR before. Looks like a new addition that they sell to DSLR users. There's also an HD2000.
The difference is the weight that's supported by the stabilizer. If you're going to be shooting with just a camera and lens, then the 2000 is a better choice -- it's cheaper and lighter.
E92 328xi | KW | AA | LUX | OEM 359M | BMW Performance Exhaust