hmmm i'd say as long as you have the necessary heroes like Neji, Sai/Kabuto or similar ninjas, you can go ahead and try. it scales according to your level so level doesn't really matter that much. but having more BP doesn't hurt because it increases your margin or error allowing you to clear the instance even if you screwed up :x
like someone mentioned, it's more about understanding the fight and the strategies involved for each difficulty and how you go about dealing with them with your lineup. i'd say give it a try and you'll have a better sense of how the instance is. in any case, you wouldn't lose stamina when you retreat from the instance, so why not? :x