Nate Pfiefer and James Bagley/EJ Etherington have much more detailed write-ups than I for Henline Creek. Use those links for levels and such. I'll update this page when I can.
One thing I will add is the impression I got from the JB/EJ write-up was that this creek was totally full on. After a few laps on this creek, I feel it's much more pleasant and manageable. The first lap tends to feel intense because it comes at you fast, but once you know the lines you realize it's pretty straight forward with minimal hazards. Totally fun and exciting stuff, just point and stroke. The exception is one drop below the bridge that requires analysis and being in the right spot but don't let that keep you from doing the run, you can always just do laps down to the bridge.
Also, portaging from the take out around Henline Falls and into the Little North Santiam is a fun option that wasn't done in the past. Reports are there are no class V rapids if you take that route (and put in below Henline Rapid in Opal Gorge which is almost mandatory to do at this flow).
Notes from my first trip.
2016 Update: There is some wood just above the bridge, rendering the creek pretty much not worth it until that clears out.
2010: We headed up to run Henline last weekend. Turned out that 3,000 cfs in the LNF@Mehema is still a good thing to shoot for. I cut some wood out of the first drop, but unfortunately the next major drop has wood in the landing which caused it to be unkayakable. The raft went over it just fine though. At higher water it may be doable in a plastic boat, but I just don't know. The portage would be a pain and on a run this short it just wasn't worth it for me so I sat this lap out and filmed. The wood was obvious and visible from the bridge (gone in 2012).
Dan and Jeff decided to head through the gorge after running Henline, which I always felt was possible at this level given you would put in below the committing part of Opal gorge. We were able to scout Sierra slot and Dan and Jeff were confident they would be able to portage Fishladder and stop in time.
Sierra was a big pourer ledge but plenty runnable. If you scout it you will find an abundant amount of lines. Safety is possible to set up but is a bit tricky getting to the spot.
I wasn't paddling this day so the rest is just from what they told me.
The big surprise is they said Fishladder becomes a big pillowy flume ride down the right side (IV+) at 3,000 cfs. I have heard from others that at 5,000 cfs a line even opens up to the left where the portage route usually is but I have not confirmed that. The rest of the run is big waves except for a drop shortly above Fishladder which Dan mentioned was big (He didn't describe it but if Dan mentions a rapid is big it definitely grabs my attention).
A quick video of the first drop on Henline which was obviously not going to work in the raft, but Dan and Jeff like to figure out how to make the raft do things it wasn't made for.
If the first video doesn't work try the one below.
They took out at Salmon falls and after lots of talk and repeatedly voicing that "I don't approve of this Dan" he went ahead and amazed us again by cleaning up on a VERY burly center line that required a difficult move and he did it R1. It was truly impressive to watch.