Preacher; If you list the manuals you have, maybe others can offer the info from their manuals. Once you explained your reasoning,,, I understood the question better. I never offer advice on reloading that isn't in print by a manufacturer that can be backed up with their testing.
If you've been loading for almost 45 years, then you are surely aware of the fact that 9mm is sensitive to bullet design & seating depth. That causes a lot of differences in what could be minimum or maximum charges.
TitanX; For the folks who do not have an easy route to testing,,, yes,,, loading test batches of ammo, carefully marked & kept separate is how most folks do try out new loads. A method I use, (And my range is 500 yds from the house,) is to load a test batch of 5 rounds, mark them with a colored sharpie over the primer, and record what each color means. Then at the range, I pull out my load sheet, select the loads & test them, recording the results, one load at a time.
Is a chrono necessary? No. But if you are a person who shoots a lot, experiments with several calibers, powders, bullets etc, then a chrono is just another great tool to help you determine more info about your loads. If you are the type of loader who only loads by strictly following the manuals, staying below maximums, careful study for signs of over pressure in YOUR guns, and once you find a load, never plan on changing it,,, then a chrono is almost wasted money. (I say almost as it's just another tool to help you know what's going on with your ammo, and many of us want as much info as possible. But remember,,, a chrono wasn't a home hobbiest reloaders tool for decades & people did just fine by following manuals.)
Preacher,,, I hope you do not mind the hijacking side info here. I hate to see an honest question not answered.