[nova]

First off,... Welcome to the Shack.

Definitely, in fact it should work much better having all speakers the same.

 

[nova]

Oooh,..just noticed that you said RS-3 II not RF-3 II,.... well the RS will work but it will not be near as good as having an RF-3 II as the center. But you most likely would not be able to use another RF-3 II as a center. I'd still go ahead and try the RS- 3 II as a center, at least until you can get another RF-3 II or an RC-3 II

 

[nova]

And if it sounds terrible, you could always use a phantom center until you get the RC-3 II.