Got it.
Thank you very much indeed anyway.
As to the current version, I'll test it this evening since I'm at work right now. Anyway, when the new mvtools2 will be released, I don't know how it's gonna handle calculations. In case MVTools2 will be aware of 16 bit stack only (input-output), it would be fine to get it working with your script and leave the interleave option for those who want to use an 8bit mask and 16 calculations.
Anyway, I honestly don't know how many benefits will bring a 16bit mask, even considering speed vs quality.