It gets pushier above 600 (depending on the East's flow too), but this time of year the gauges can be a little deceptive because they are reading low-altitude snowmelt. But regardless, word around is that Oh-Be is running good, as is the Slate and East. I've heard conflicting reports about Daisy. CB locals can advise better.
IMO if you are solid on Tallulah (or maybe even on Sec. IV at 2.2'+), I don't think OBJ at low-med flows would pose a problem. It's pool-drop, but the slides are long and not places to flip. If you just run from Heart Attack down to the takeout above Avalanche, it takes out some of the bigger slides and makes the run a little easier. YMMV, scout and decide for yourself. There will be plenty of people's lines to watch before you do.
p.s. We observed at least two bears, one unusually large one in the fringes of the campground last year, so keep your food and garbage policed.
Just to clarify, you want to put in BELOW Heart Attack. It is pretty easy to figure out which drop HA is, but if you have questions there should be plenty of folks to ask.
It can be very intimidating if you've never boated 4" of water running over a sharp slate riverbed. THe first drop you see is a huge slide ending in a bunch of avalanche debris. The first time I saw it I thought "you've got to be kidding." But it boats much easier than it looks. I recommend doing the East first if you've never boated anything like that. If you thought the East was stoopid easy then you'll like OBJ. It is a super fun creek but be careful. Not once have I been there and not seen carnage - compressed disks, bloody heads, sprained ankles, dislocated shoulders, broken boats and paddles. They don't call it Oh-Be-Careful for nothing. It's not a hard run but being offline can hurt. The flows vary significantly during the day. Morning runs are lower. Evening runs can be big. Run at midnght like Gary E and Chorter for maximum fun. 600 to 700 on the slate is optimal in my opinion. The lower half gets really pushy at higher water.
Livingston, I think you may be confusing Heart Attack and Ankle Breaker.
Few people run Ankle Breaker, and then only when the flow is really up. Heart Attack is the normal put-in for almost everyone, you get in on a rock about 15 feet about a 17-footer. Pretty much point-and-shoot, and most folks boof it. Heart Attack is where most folks park. Ankle Breaker is a few hundred yards more upstream and is more on the hiking trail than on the jeep trail, IIRC - it's got a shallow landing zone, hence the name.
Ditto on first impressions driving up there. My first time there was in 2002 and I just about pissed myself when I saw Avalanche.