Your not likely to find any secondhand XL2s now are you! Canon are not THAT great for low light (Even the Xl2 - although better than the Xl1s) just about the best low light cameras in that price range at the moment would be a Sony VX2100 or PD170. There is no need here to compare the Xl1s and XL2. There is so much information on the net I'm sure you can do this yourself. But it all depends on what your wanting to achieve. For example if you must have 'real' widescreen then perhaps you only have the Xl2 as an option. Are you not able to hire one out and run some tests?
First B/W semi pro music video in the bag! More to come.
Dual Athlon MP 2800+ 2 Gig DDR Ram Pinnacle Edition V6.1 pro 2xXL1s