you can have plenty of chainline deviation. there may be some increased wear - may or may not be noticeable. same goes for noise - may or may not be noticeable. if your chain tension is proper and your chainring is close to round (out of round chainrings lead to unevenly tensioned chains - tight spots and loose spots in the rotation), you won't throw a chain.

teiaperigosa, most people can't accurately measure their chainline to within 1mm.

i'd say that within 10mm, you're fine, but that's just a guess. i've certainly ridden setups with bad chainlines - with absolutely no problems.

1/8" chains have plenty of side to side movement, though not as much as a 9 or 10 speed chain, obviously. try this. remove your chain from your bike. hold it at one end, let the rest dangle. move it from side to side. feel how much movement it can handle. plenty.