Still getting to know mine, need more quality time...
So far one 'fault' bothers me. Power shown is a calculation, and IMO not a very useful one. It uses the target voltage and measured resistance (at the start) to calculate the power that should be happening, not what is. Run this little test: Run your Bender, Hammer or Hercules for say 10 seconds. Notice how the power stays constant? Then power off for a second and hit it again, notice how the power is now much lower than a few seconds ago? New resistance number. This gives a huge error in the displayed power potentially. Minorly, the voltage used isn't actually measured near as I can tell, it just uses the value you dialed in.
I also had intermittent reset issues that came back to the Iris contact being further up the tube than Persei near as I can tell. I had to screw the batteries up way past flush to get it to work right. Taking the top I'd been using on Persei off and putting Iris on was a failure. This might be corrected later, for sure I see no reason to have extra length added to the Persei just to use this top (which is itself taller than Persei).
OF