Hi
So far I know the MG505 was released some days oor weeks ago that's why you can't find any reviews yet.
Either wait until the first reviews come in or check out the review of the JVC MC-500.
I assume that the MG505's video performance will be similar to the MC500, there are rumours that the MG505 is like the MC500 but with harddisk.
If you want to decide between the SR100 and MG505 then please note that the SR100 is a little bulky and users have reported some noise issues.
On the other hand the video performance of the SR100 should be great, even in low-light.
Regards
Sektionschef