I'm also about 20% down this month which I blamed on the Easter holidays but yesterday my sales went down by about 50% on normal. I hope that it was just a one off and not a result of us being pushed further back in the search because of the exclusive + images.
I'm down everywhere this month so far but mainly because of the Easter holiday. Sales have picked up again nicely now.
Sales at IS are still in the normal proportion to sales elsewhere, currently at 33% of my total. Yesterday was my highest earning day of the month and the second highest for downloads. No obvious effect from either the downtime or a change to the best match.