I have a RK 4x12 straight cab and I really like it. It really lets you take full advantage of the RK's switching options with one cab. I've never owned an oversized recto cab so I can't compare it to that, but I do have a stiletto 4x12 cab. I loved the sound of the C90's and V30's mixed, so I ordered my stiletto cab with an x-pattern. To me the stiletto cab seems a little tighter. The RK 4x12 has a very huge sound to it with the 1/2 open back.
As far as tone goes, that's always going to come down to personal preference. I would say I generally use both sides of the cab together because I think the different speakers compliment each other very well, but it is alot of fun to experiment with the endless tonal options of using one side vs. the other.
Good luck!