K5 as black & white HDR shooter; will the K5IIs deliver sufficiently more for upgrade?

K5 black & white HDR

When I purchased my K5 I envisioned using exclusively as a black & white shooter. My HDR shooting kept me shooting some color. Here is a black and white HDR example. I purchased my K5 at the end of August without knowing that the new models were about to roll out. The latest model had me considering it for more potential detail, but, how much more does one need when shooting HDR with some tone mapping?

Thoughts?

--
Joe