Thanks for the compliments.
"Can you give any more detail on how the 4x10 pairs up with the Mk V? Also, what kind of music/tone are you going for?"
I was concerned I wouldn't like the 4x10 with the MkV but i was wrong. I spend most of my time on clean or midgain settings although I really love high gain. After reading your post I decided to a/b the 4x10 with RK4x12. They both sound good. High gain sounds are better thru the 4x12 and the cleans and mid gains are better thru the 4x10 as I would expect. The 4x10 is very open and fills the air around you with it sound. When I gig I don't get to use much high gain so the 4x10 is a better match for me. Also, think of fender bassman and vibroking as far as 4x10 sounds go. It does sound good with high gain tho. I just had to turn the presence down to focus it more. The RK4x12 was very directional in the outdoor gigs I used it on. I haven't got to use the 4x10 yet. I think I'll like it better for what I do.
hope I didn't ramble to much.