I like the products but have had some consistent issues I've poked at here and there to try and understand. The issues seemed pretty consistent across G8 and G9, but in trying to sit down and go through everything I recall for this thread I ran into changes or differences. I'm going to hold this to G9 for now.
1) have you seen different versions of the Daz3d software break or fix issues with your products as they implemented changes? I'm not a hardcore user with serious time to indulge - I tend to get some time every couple of weeks to dabble and it seems there's always an update or two to apply.
2) If I apply Growler NG Pro to a character sometimes when I move the character the growler will double the movement - if I move the character to the side one unit the growler moves two. Sometimes it doesn't move at all.
3) In one case when I applied two different hairs to the same holder and applied a seated pose, one of the hairs stayed attached as desired but the other was, say, 4-5 inches higher on the body so the figure looked like it had a REALLY tall bush.
I have tried to limit today's experimentation two just a couple of figures, understanding that different ones may have different issues. I most recently was playing around with "JS Cleona" for G9 but also went back and experimented with the default G9 figure.
I have tried both autoloading and manual loading as per the Growler NG Pro G9 README. Most of the time If I do the autoload with full "holder plus hair" nothing happens or loads. Manual loading of the holder first and then the hair will load both, but not connected in any way, even if I select the holder first and then the hair (i.e. it will load at the bottom of the scene list separate from any other element). If I subsequently go to parameters and perform the "fit to" as per the read me, it completes without any error but does not follow the figure or holder if I move either. If I drag the growler in the scene window so that it is parented to the holder it is more reliable, but this doesn't work as well with the full body hair as I can only parent to one item and one of the legs or arms is always off.
A current Cleona figure with the hait fit to and parented to the holder is one of the ones that is "double moving" when I move the figure. I have seen this before in G8 but was not able to duplicate today and am not sure if it is figure-dependent or if something else is the cause.
When I chose the default G9 figure, changed all feminine parameters to 100%, and then loaded New Gens, the option to fit to in parameters was effectively "greyed out" as in I could not open down to the general/misc section to choose the "fit to" option.
I should probably stop here for now, this is a little more information and chaos than I intended to start.