We just got off the Main as well with a July 24th-29th permit. This was my first time down, Corn Creek was about 2800.
I found Black Canyon to be the most difficult as we could not clearly see the right side and after watching several boats hit rocks we were a little leery. We ran right anyway pulling hard off the right bank and ran clean, very fun rapid!
Big Mallard was easy, looks tight, and I did smack an oar on the rock on the left bank, but ran clean between rock and bank on river left, fun waves at bottom.
Elkhorn was fun, ran far river left, then once below big dropped moved left, then back to middle and continued to dodge rocks and holes the rest of the way.
Watch out for Little Stinker as many boats in our group hit big rock on river left, very pushy at low water, start center move left and ferry for your life river right to avoid it.
Vinegar gave us a little pucker factor as we came around the bend to find an upside down 15 footer. We almost flipped a boat here, run center left for monster ride, not recommended. I ran center right for clean run. Awesome run, the Main is my new favorite.