Aftermarket telephoto lens for the LX7?

Sure, if I really want to get serious about some extra zoom in a compact, I should get a second camera that does the job really well.  I understand that, and I am currently considering some options.  However, it's hard for me to justify a second camera purchase right now, and that's what makes the idea of an additional lens for my LX7 an attractive option.  I've come across a few, but to be honest I have no idea about what is decent and what is not, because I can't seem to find any reviews.  So, is there anything out there that is worth the trouble?

Thanks in advance

(2x would be good enough for my purposes)