Using the characters you mentioned....
Sakuya
Reisen
Aya
Suika
Okuu
Aya's still mid-high or so. She's not bad at all. And no, Sakuya's damage output is plenty good. Any better and she's just be broken. I don't think you appreciate how stupidly easy it is to get damage with Sakuya. All you need is a half-assed okizeme game and you've suddenly got multple guard crushes and free knives. That bitch doesn't even need skill cards in her decks to win.
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@Sungho: that other video I uploaded, the one with the Yuyuko and Iku, has a breakdown of why BEs happened. I hope that helps you out. I'd say it's a bit too advanced for someone just learning to BE, though. The only things to really keep in mind when doing it are a) "Do you think your opponent is going to use a melee move after the one you're BEing?", and b) "is it worth it?" Honestly, if you're questioning this, you're probably not at a level where BEing is worth it at all as your opponent probably won't be able to capitalize on an orb being gone (hell, they might just play a character with shitty pressure and end up the same). Also, if you ARE playing against other people, I'd say to focus on using BEs defensively at first, just because that's how I learned to do them. Though it's really up to you in the end.