I found the R9 to be very thick and bassy.
The SR2’s are a lot more open sounding to me. Great bass and forward mids. They feel much flimsier due to the headband design. Overall I find the sound much cleaner and more articulate. I found the treble a little recessed, but that works for me.
When I need the Boom, I use my Cascades. The R9’s, in the end, just lacked clarity for me.