Thanks for your detailed reply. The engine that we use, supports Linux export by default, so it's not a big deal exporting for Linux as well.
What is really essential for us, is not to have any kind of technical problems and since we're not Linux users and also can't test our game in all Linux distributions available, we are a bit hesitant of distributing the game.
We prefer to sacrifice a few sales but be 100% sure the our game runs as it should in all available platforms than to run in 95% of them but with a small percentage experiencing problems and regretting buying our game. On the other hand if there was a significant percentage of users that would really want a Linux version we should probably spend the time and test the game in more Linux distributions.
We will need to give it, a bit more thought.