Hi there, spunk.funk ... glad you mentioned the plug-in!
weybrew .... did you happen to already have any older plugins that had special print functions (like the Print Preview plug in? -- which, by the way, has been timely about keeping up to date, and should work with your latest 44.0.2 version Firefox) ... if you happened to already have an older, aging plugin - some of these are causing problems in Windows 10. You could remove them (since they are so easy to reinstall), and see if the built-in preview in Firefox works OK. If that's all you need, you're good. If you'd like the extra features provided by the Print Preview plugin, it won't hurt to give it a try.
I did a fresh install of Firefox on a Windows 10 test laptop, and the Firefox's Print button now goes straight to a print preview of sorts, which apparently works OK with a fresh install (with no plugins). I found its preview to work OK, but it seemed fairly basic at first glance. I enjoyed the 44.0.2 version overall (Chrome is my usual browser), I thought the features and look of Firefox has a brighter, cleaner look. Nice.