I get 857 and some change mh/s with the 864 firmware.
But not long term, or? The values averaged over the last 5s might fluctuate (I even see higher values than clock rate now and then), but if you let the device run for a day or so, the hash rate should settle to the values I gave - at least that's what I see with my Linux driven BFLS.
That is the average over a day +. The only time the thing comes off of 857 is when the long poll hits from the pool.