Gil, first of all, Thank You for creating this Superstar-ish version of morphing in xLights. It's amazing and the work you do is not thanked enough. I wanted to make sure you were aware I wasn't sharing any disappointment in what you've built, at all. More just making sure I have a proper understanding of expectations. I do agree that you have improved on it.
For head and tail length, your explanation makes perfect sense. I looked everywhere for "effect backgrounds" settings but I could not find it anywhere...even on the forums. Would you be so kind as to add some more info around where I can find that so I can refer to what you're talking about?
No worries about twinkle and shimmer. Thanks again Gil!