Used the BMS last night on a 60 - 70 foot descent in a stope on a very mucky 10mm rope.
With the rope bag hanging below me (i.e no rope weight below the descender) I found it necessary to use the hyperbar (in effect five bars).
Having climbed back up the stope I started to de rig only to find that the rope bag had jammed at the foot of the pitch. I dropped the pitch to free it. I found that with sixty odd feet of rope below me I only needed four bars.
On both occasions heat dissipation was excellent, the bars still being fairly cool at the bottom of the pitch.
The descent was smooth (compared with my companion who was using a stop and found the mucky rope an issue). It is worth noting that the stainless bars were faster than aluminium would have been.
Although I am still very much in the learning stage with the BMS I am rather chuffed with it.