Very well executed, IMO. Some other people have mentioned that themeforest doesn't obfuscate and they're doing just fine, which is true, but they also have additional assets that are needed in addition to CSS. Namely, PSDs.
One way you could increase incentive to buy instead of steal is only show CSS on the preview, but download the LESS file on purchase (if the author used LESS). I'd certainly be more interested in a LESS file.
In the end, I wouldn't worry about it too much, like someone said, people who are gonna pay are gonna pay.
OT: Are you using some sort of "food ipsum" generator for the StackLayer theme? I love it.
Yes, the additional assets are the big gotchas (especially with themes that have text embedded in images) and I like the idea about including the LESS source. I'll get on adding that to the StackLayer theme!
One way you could increase incentive to buy instead of steal is only show CSS on the preview, but download the LESS file on purchase (if the author used LESS). I'd certainly be more interested in a LESS file.
In the end, I wouldn't worry about it too much, like someone said, people who are gonna pay are gonna pay.
OT: Are you using some sort of "food ipsum" generator for the StackLayer theme? I love it.