We ran it at about 400 cfs in 14 and 16 footers. It's doable, but takes some work. If you're good at reading the channel at the end, you'll be able to get through without even walking the boats in 14 footers.
We ran it a couple of years ago at about 500 cvs (then it came up some while we were on the river - maybe 600 tops?) and it was pretty easy really.
The only real challenges both times were Government and Gypsum Creek (?) right there at Mexican Hat. Gypsum Creek is read and run, but the lower the flow, the harder it is to find a real channel. You might get hung up on the occassional rock there, but not too bad.
Government is always worth a scout, but at low flows, there really is only one decent line. And yes, it involves avoiding the rock in the middle. This last trip, we hit Government at about 350cfs and got through OK. Momentary hang ups at the top, but slow enough to get off the rocks, adjust and avoid the middle rock at the end.
There was one other rock garden that I am not sure even has a name. At 500 cfs, the line was far right against the wall. At 350-400 CFS, that was the same line, but we did have to get out and walk all boats through in ankle deep water. LOL Only the mini-Max had a line through that one, but it was the exception and not too much work.
Just pray for calm days. A headwind and that trip in low water is a LOT of work to row out of there!