Grum,
Although myself a newbie to the forum welcome.
The sort of questions you ask usually produce more answers than questions. But basically with the right expertise many cameras can be used for many subjects..................50 /60 years ago 5"x4" technical cameras were used for sport.
But things are rather easier these days, cameras have a more " all round" capability with less expertise from the user, although as Orwell would have said "some are more equal than others". The trouble is your requirements are poles apart, sporting photography to casual night club snapping. The answer in plain terms is the GF! isn't the first choice by a mile for the former but would certainly be a major contender for the latter.
Without going into great confusing details get the GH1, OK. it's a compromise but it's small...............check it out. But for your needs there are loads of DSLRs available at budgets to suit most pockets, all of them are probably better for sport then the GF1. But for ltravel/ casual work perhaps only a Leica M9 would be better than a GF!. ( a very debatable subject ).............with a decent lens? ££7,000 ish .
To summarise, and it's only my opinion.
1) Sport..............0%
2) General travel...100%
3) Casual snapping...100%
But again, it's my opinion and although 0% for sport might appear draconian the GF1 would certainly not figure on the my list. I'm not saying you can't photograph sport with the GF1 but that there are far far better options at far far lower prices.
Brian.
P..S. Funnily enough re-reading the above I realised that if the question had been based re buying an M9 my answer would have been exactly the same.
I see the GF1 as a niche type product, exactly like a range finder Leica but automatic. Now if only it had a decent viewfinder.
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