[Edinburger]

One short stay shouldn't have any negative impact in future. Most people understand sometimes things don't work out or you get an offer you can't refuse (in a good way). If you had, say, three short stays in a row, future employers might get nervous.

I would go where you think you'll be happiest where 'happiness' is a linear equation comprising money, interesting work, nice colleagues and whatever else matters to you.

A word of caution: make sure nobody at your current company finds out you're talking to the new company until you have an offer on the table.

Good luck.