The only LAN I have competed in is WGG, a local tournament in Ontario. I placed 3rd, behind e2k Composure and Impulse[unofficial] (Consisting of Knockk D, Twokit IMP, Improvize, and pX I Tupac).
On my team was me, Valentine ily, and two other players not registered on this website. We had about 2 days of practice. Not a major accomplishment, I know, but I have gotten a job last week (Yay!) thus, I will be able to afford to go to MLG events now.
For online tournaments, no, I have not competed in any other than participating in GB Ladders. I have had interest in joining an online tournament, but have been unable to find other people who were willing to participate.