microgamer
[10] Knight
Pretty much sums up my view on the benefit of online in terms of competitive play and bettering yourself as a player; learn setups and matchup experience online, then work on execution offline.The experience gained from playing so many people coupled with offline refinement...
At the same time, there's a lot to be learned from going to tournaments and getting a lot of (casual) matches in with good players. If the community is friendly, the players will point out the things you need to work on; if not right away, at least hopefully after you ask them.