I enjoy doing the comic style renders, and will be doing more in the future, glad to hear you like them. The Girl7/Guy7 characters are some of my favorites and the more recent stuff is Girl/Guy 7 converted to G8 :)
I would recommend using the G8 utilities for G8, and G3 utilities for G3. Many of them will work cross generation, but a lot, especially the expression utilities, will have pretty ugly results unless you use the ones specific to the generation they were made for, because a lot of joint rotations changed from G3 to G8.
As for trimming down and combining the utility sets, the most recent version of a utility pose is always the best one to keep, the older versions can be overwritten or deleted. Some of them haven't changed in years like the zero expression upper/lower, I just go ahead and include them in every pose pack that has expressions so there's like 20 different versions of the upper/lower zeros, but they're all essentially the same .duf file.
A side note: The dicktator shaping presets in the HJ and BJ sets are numbered to be applied for a specific range of poses, if you aren't using the right shaping preset, you may be giving yourself extra work aligning the hands/mouth to Dicktator
Perhaps at some point I'll combine everything into a single "toolkit" that has all the most up-to-date versions only. The downside of that would be I'd have to update that toolkit everytime I thought up a new utility pose, but anything is possible. :)
Hope this answers your questions :)