Tigger, I've come to this thread late but you have made a great choice I run A Canon XL2 and XM1 also owned a XL1S previously. One thing you may want to think about is the Canon adapter and then just go out and buy yourself a cheap Canon USM 70-300mm lens F4-5.6 (pick them up around £90-£100.00 on an auction site.
You will then have a nice light lens that when added to the Canon adaptor to your XL1 and the lens turns into a 2000mm

great wildlife lens due to the smaller sensor on the XL1.
Also save you having to buy an expensive rail system, although you can of course add much larger faster lenses, if you do eventually have a rail system.
Just don't breath near it if you have it set the lens to 300mm (2000mm on the XL1)

And have a nice heavy tripod, Although when i first got mine I shot seals off the south cost of the Isle of Mann with a Velbon DV 7000 and managed to get usable footage withit at 300mm (2000mm)