Hi, Simon,
Thank you for your comments. Did you keep your Pentax gear, or have you gone "all-in" with Fuji? I kept my Pentax gear, as I have more k-mount glass than I plan to get for the X-S10. I'm using the Fuji with the 16-80mm as a travel friendly, versatile setup, which has been working out very well. We'll see if I end up leaving the Pentax home permanently and slowly add more Fuji glass.
Your comments about the OVF versus the EVF are interesting. I was concerned that I would really miss the big OVF provided by Pentax, but so far, it hasn't been too much of adjustment. Another noteworthy difference for me favoring the Fuji is the better autofocus. You are correct about the weather resistance of the Pentax, which I always found reassuring. Of course, there are other minor differences between the two systems, but nothing that's too difficult to handle. Most importantly, both Pentax and Fuji, in my opinion, provide great image quality.
Because it's a new toy, I've been shooting with the X-S10 more than Pentax, but someday I should shoot them side-by-side for a comparison. I'm really happy with the X-S10, and it sounds like you are, too. Happy shooting!
Cheers,
rick