I have played Ooana's Blackguard fairly extensively. I sharpied out the rogue text on the account of the fact that bitterblossom is about the last card in my list that needs a narrow combo to make it stronger. Reckless Waif didn't like that decision, but she works for me so she had to deal with it.
I didn't particularly like how it played. Very rarely would you get a situation where Blackguard came down midgame with dudes on board that could get through where the discarded cards or forced blocks made a difference in the winning the game. In fact, I can't remember that happening at all.
Instead, what I remember is someone going cloudfin->blackguard and winning off of there 1 mana hypnotic specter if the opponent didn't have removal or blackguard coming down later on and having minimal impact because the required elements didn't line up (having a dude with counters on board that the opponent can't remove or favorably block or the dude only getting in once before the blackguard or dude gets removed making it a convoluted
Wrench Mind variant).
I guess if I didn't run evasive one drops that can get counters and sharpied something different on top (even if I cut bitterblossom my comparatively large cube only has 5 rogues) then the card might have play, but I'm pretty cold on it at the moment. Unlike the other counter lords it doesn't "change the math" on the table and when you are committing multiple creatures to the board to get an effect I'm not sure you can afford to be subtle.