Pete, I'm taking a cautious approach because of the newness of the Blunami cards and the conservative nature that was instilled in me in engineering school 50 years ago. I suspect that 95+% of the time, the 4408 card will perform just fine in many engines, regardless of stall current. Unfortunately, both of my steamers with can motors and "conventional" control have Mabuchi motors, so they'll get ERR Cruise Commander conversions.
I looked up the spec sheet for one of the more popular Pittman motors a few weeks ago and found that its rated stall current was nearly 15A, which surprised me, given discussions on this forum. One must consider not only the average current seen on meters but also the peak current that has the potential to activate the card's protective features. PWM is used in many motor controllers (including Blunami) and the peak current during a low-duty-cycle pulse will be far greater than the average. I'll admit to not having looked into that in any depth. But I do know that my DC power supply often went into current limiting when the Shark's motors were wired in parallel and the current limit was set to 2A, while the supply's display never showed more than 1.4A. This was worsened by the faulty pickup rollers (later replaced) causing intermittent losses of supply voltage and therefore current surges upon restoration of conductivity. In that circumstance, the Shark did not operate smoothly nor reliably.
I did run the Shark with the motors wired in parallel, with pure DC power, and the Blunami card in-circuit. Replacing the faulty pickup rollers resolved the reliability issues. Displayed currents reached well into the 1-2A range at speed. The linearity of the Bluerail speed control left lots to be desired, but it wasn't tuned to the engine at the time. It appeared that parallel motors was a practical possibility, as long as a DC>DC buck converter board was used for regulation and I was willing to accept the (unlikely) risk of a stall. In the end, the series connection gave me all the speed and pulling power I desired along with better control linearity, compliance with the Soundtraxx specification, and the option of not including a buck regulator. I might make different choices on a different loco.
As long as we acknowledge that risks exist when operating outside the manufacturer specifications, let's all pursue what we're comfortable with and share our results.
