Im going to add a sort of conclusion to my thought process after more demo's and soul searching....
It is somewhat of a boring solution - but i've decided to quite literally do nothing at this point in time. The lack of lenses (and overall final price tag) of the S2 system has put me off (compared to pricing of the Pentax).
I will instead wait for the inevitable 1DS MKIV - since I have a big investment in Canon high end L glass and frankly really like the ergonomics and ruggedness of the 1 series cameras. This point was really hammered home to me on picking up all of the MFDB's that I played with and their respective bodies (except the Leica S2). Its a personal thing.
It has been a very interesting few weeks looking at the options out there (in quite some detail). The hands on tests have been the most eye opening for me and are ultimately what has convinced me to wait for the 1DS MKIV.