I think if you buy an o-ring chain for a smaller bike you have invested more than you really needed to in a chain. This is not necessarily a bad thing , as you will pay more attention to it , and , if you buy the nice gold one you feel inclined to clean it so you can see its shininess .

O-rings seal some lube inside the rollers and reduce wear so they do no harm. You will get more km from the chain , but the real benefit is not having to get out your tools every 300km and adjust it.