I can't compare them, however I have used the backscatter one a bit. Couple notes:
It has 'Optics by AOI' stamped all over it so, very possibly coming out of the same factory... (if considering build quality)
With the Olympus housing there is a bit of an issue with flooding the space between the lens and the housing. The thread is so deep that it would create a sealed air bubble against the lens by blocking the vent holes in the mounting ring. I found that when I'd installed it on the boat I needed to unscrew it several turns and then flip it around to get the bubble out (or just take it off all the way if it was a calm dive). It was also possible to do this in the rinse tank ahead of time but it did prove to be a bit annoying at times.
I found the 'zoom through' to be less useful than it would seem to be in theory.