Is there any way to remove the 10 recipents limit from the SMS app?
Since your phone is rooted you can use  Wanam Xposed 

Note that the framework itself doesn't add any functionality, but once installed you can download (via the framework itself) modules that have custom functionality. Wanam Xposed module has many tweaks for stock Samsung Touchwiz ROMs, GravityBox has many for morer 'stock' type ROMs. You can change the SMS limit through either, in the default SMS application. 

Please read the XDA Thread on this module as it has a lot of detail, and clarifications.
 XDA Thread