Played for near on a year and half weekly. Most combats were done using miniatures (not all, I will admit).
We used them with a map, with squares or hexes. Worked fine. It is a bit odd that the miniatures are actually too small (the map scale is 1" = 1 metres, when the miniatures are on a scale where 1" = roughly 2 metres), but other than that I never had any serious issue with it.
For Deathwatch we did on occasion use different scales (1 space represents 2-5 metres) as longer range fights were more common. Thruthfully at this point it was a bit fiddly and didn't work that well, but then we weren't playing it as RAW (and Deathwatch had more rules which simply didn't work with miniatures, like hordes).
I am not actually sure what you mean the "distances are a complete and utter mess on the tabletop"? Do you mean the extremely long ranges? Then I can agree that you couldn't do long range fights mapped, but then long range gunfights shouldn't really be mapped. Anything past about 50 metres is not worth mapping. It only really matters at short distances anyway.
I am not sure why the fact it was in metres makes any difference? The difference between "3 feet" and "1 metre" are so not worth bothering with on a game of this scale that the two are functionally identical (though the metres figures are easier to work with, though I guess you could just translate into yards). I never saw any problem occuring because things were measured in metres rather than feet. Maybe it's just because we use both in Britain that the issue never even crossed my mind.
Edited by borithan