Republic to take 50 E-175s as Q400s head for Flybe - 9/17/2014 - Flight Global

According to this article, it's interesting that Flybe actually wanted Qs, and was looking to get out of their 175 orders. So this was basically a three-way trade:

YX gets rid of Qs (which they had to offer $10K signing bonuses to get new hires to fly), gains some 175s to offset the 6037 145s going away.

Embraer gets more business. (according to a Dallas News article, these are not the 47 options RAH had, this was a totally new order)

Flybe gets a plane that is cheap to operate. The Q is probably more better suited for a European route structure anyways (lots and lots of super short hops)