RTi/RTIa for surrounds

Howdy,
I am looking to replace some horizontally mounted Boston Accoustics CS226 towers I am using as surrounds. (I'm now learning that this is probably not ideal.)

I have some RTi12's up front, CSiA6, and a DSW660wi.

My receiver is a Pioneer SC-91.

Would RTi5s be preferable in this case?

thanks!