i have spent very long periods shooting M cameras and x100s (2 original x100). i have worked on both and as per image quality/file quality the x100 is absolutely ok with me. some might say i have low standards in the pixel peeping/corner sharpness/bokeh department and honestly they are right. that said, i have had work run regularly in print etc. from the x100 with no editor complaining. i have also made gallery prints regularly at 16x24 from jpeg files and again, no complaints. horses for courses as they say.
what i can talk about is the user interface with an M and the x100. i have yet to shoot an x100s. as mentioned, the 'buttons and dials' end of things leaves some very frustrated and at times, myself included. what really bothers me about this is that solid, simple interfaces and the logic that goes into them is not fresh as of the digital camera inception. why something like a compensation dial being loose or easily moved is overlooked when the camera is launched, baffles me. as well, the buttons and the ability to press them and quickly make changes/move thorough the menus on the x100 seems to have slipped under the radar prior to release. these things really should be unacceptable at this stage and i can't get past the WTF? point when i start thinking about them.
the af performance of the x100 is acceptable to me. i have, in the past shot nikon v1 cameras as they are blazing fast, and in the field that can be a real relief. the x100 is nowhere near as capable in this regard. it often stumbles badly if you make the mistake of letting it go to sleep. i have a well entrenched habit of constantly working the release to make sure my cameras are ready to go but again, why are we still battling this core issue? the reason many photojournalists use big pro cameras is because they are fast, very well thought out in the interface and intuitive. so, yeah... with the x100 i work around the 'speed of response' issues by carrying many batteries and keeping the camera awake.
i work around the comp dial by taping my cameras up a lot. not for stealth per say... more to keep settings where they are and covering any lights. i remember the canon g cameras i was using for a while needed 4 or 5 pieces of tape just to cover all the stupid lights. bloody christmas tree.
manual focus on the original x100 was a disaster from the start. why the camera came on the market with the manual focus concept it did is once again, beyond me. this isn't 1st generation stuff solely dependent on sensor tech. in my opinion, if a compact camera isn't equipped with peaking in one way, shape or form, a mistake has been made. another small change could have helped the camera out and it is as old as the hills. dof scales on the lens. or at least a dof representation on the manual focus scale of the optical finder.
now, with all the above, i still shoot the little things and most likely will upgrade when it is needed, to the x100s. the files are great when the light is good or bad and with some user work arounds it is a very capable little machine. hopeful FUJI will iron out these core concepts with the x100 line as they could be an absolute classic for documentary/reportage/journalism.
the M body is, as most already know, incredibly solid, simple and with a very well thought out approach to user interface. with very little practice and work, you can be quick as a hare. i don't shoot digital M as my experience with Leica service has not been good. i am not one of the types who considers a 2 month turn around on repairs acceptable. they are temperamental and buggy at times and service is a real consideration for a few working photographers i know. i suspect though, an M9 might be in my future and maybe this area has been improved upon at Leica.
so, different beasts entirely. but can the x100/x100s do the same job? well, if you are comfortable with workarounds and dealing with some of these issues then yes they can. buy yourself 4-5 batteries and fast cards. go to town.