A non-exclusive photographer who has a lot of good recreation photos on both iStock and Shutterstock contacted me today with the observation that in the last six weeks his images on Shutterstock have been outselling those on iStock 3 to 1. (This is not because of new uploads on Shutterstock.) For the previous two years iStock was outselling Shutterstock 3 to 1. Is anyone else seeing this trend?

It seems to me that there might be at least three reasons for this switch.
1 - iStock has raised its prices, particularly with their exclusive collections and they may have priced a lot of their former customers out of the market.
2 � iStock seems to be pushing more exclusive images to the top of the search return order. This makes sense from iStock's point of view because the images sell for higher prices. They also keep their exclusive photographers happy and encourage more to go exclusive. However, because there are not as many low priced images available on the early pages customers may be getting the idea that all of iStock's images are now much higher priced.
3 - Many of the non-exclusive contributors who are also buyers are upset by the reduction in their royalty percentage and when they need to purchase images they may be going to Shutterstock in an attempt to send iStock a message.
 
Any other idea? What do you think?

I agree with all three of your reasons.  And yes, SS sales have been booming as Istock's have been declining.  It seems to be a pretty widespread phenomenon if you read the stats threads for the last couple of months. 

Yes!  ironic!  but almost on the same date as the new IS, best match, came into operation, all three Shutterstock, Dreamstime and Fotolia,  went right up,  cant just be coincidence? especially Shutterstock.

Even Alamy!  is showing a 30%  increase.

Having said this, my images are very nieched but even so?

One of the more interesting things I've noticed at Shutterstock is that the 'On Demand' downloads have picked up quite a bit, which is part of the reason Shutterstock is bringing in twice as much for me now than any of the other agencies.

exactly!  and a lot!  so have ELs.

photographers get 5 * $1,88 = $9,4

photographers get 5 * $1,88 = $9,4

no, the price for "on demand" varies. I am getting $1.17 or $2.70 per sale