Just another point to add to the discussion, safe-n-sound are the only brand that actually test there seats so in my mind they are the only ones that should be on the market.
The reversible seats also have so much extra padding for our little bubs in the early days that i really doubt that the capsules are any safer than a reversible.

We used our safe-n-sound reversible for so long with DS and we were completely happy with it, but it really is a personal choice.