Has anyone ever used the Letus 35 Flip Advanced on a Canon XL1? The XL1 is not particularly good in low light so I think I will have to always add lights on shots that previously never needed one. How about vignetting. I was told that shots have vignette using Letus 35. I think that if the Letus 35 Economy is not that far in performance as compared to the Flip Advanced, I would buy the Flip Advanced and keep the $200 savings (the Economy is $900; the Flip Advanced is only $700). From where I live, $200 is a lot of money. Which is why we're also thinking of substitutes to the Letus. Thanks.