Really it depends on your situation. In a solo/small group/full group type playstyle, Brigands and Swashbucklers are pretty much interchangeable with no noticeable difference. We do about the same damage, etc. The only reason I would see to betray is if you were in a guild that wanted to raid and could not recruit brigands. Having a brigand all the time at your raids is quite a boost when compared to a swashbuckler. This only applies to one brigand tho, if you already have some, may as well stay as a swashbuckler because we offer some unique debuffs that brigands cannot.