I'm running Sierras, both up to 80% on the castle controller, the 18 amps of battery should yield (on paper) around a 2 hr duration at cruising speed of 150fpm.
My goal for this Sierra is to be a loaner or a back up scooter. As a backup, I think it should have more than 1/2 the range of my primary. The 12ah dewalts give ~480wh and the 15ah should give ~600wh. I have no idea how the efficiency of the sierra motor compares to the efficiency of my piranha but shirley it can't be so bad that I don't get at least 1/2 the range. My piranha currently has ~777wh according to battery space.
I will try and get some actual data and report back here.