The valve seal problem was much more common with the first year or two of the M103 production.

You did not put a selection that matched my situation best so I picked your top choice. I have NEVER had oil consumption problems with my M103 and it is now at 315,000 miles. I had a non valve seal related issue at about 176,000 miles that required head removal. I, of course, did a valve job including guides at the time.

If you buy a car that is not using oil and take care of it including frequent oil changes as well as antifreeze change every couple of years, it should serve you well.