I don't have one and I really don't want to get that serious about shooting or reloading. Maybe I'm missing something here and I'm not trying to be rude or disrespectful.
When I recently started reloading I started doing my workups at 10% lower than the lowest recommended powder range for my powder and bullet combinations. I loaded several rounds usually about 10 of each in tenth grain increments. I go to the range shoot them until I either find a good group or I run out and continue the work up until I find what works best. Usually it doesn't take much to find a load that shoots good as or better than the cheaper factory loads.
I loaded probably 2000 rounds before I ever got a chronograph. I eventually did because I figured unexpected velocities from certain loadings might give me an idea if something else is off indicating too low or too high of pressure. I found it interesting also to test my defense loads out of short barrel guns. I wonder sometimes about velocity loss due to barrel length, and if it will have an effect on expansion. It can also be a good tool if you are loading pistol ammo, and then also wanting the same rounds to work in a carbine.
Example: I loaded a bunch of 357 magnums with 158 gr platted bullets rated for 1500 ft/sec. Out of a 6" revolver I was getting around 1200 ft/sec average, and that was a max load. This was disappointing to me as I can easily exceed that speed in a 5" 10mm. So I found it useful in that it indicates I may have a problem with that gun. Then I noticed as the charge increased I was getting bullet fragments splashing back at me, and a piece actually cut my ear bad enough I had to stop shooting to clean myself up. When inspecting the gun I saw that lead and copper are piling up between the top of the forcing cone and top strap. So I think I have a timing issue, or it may be an excessive barrel cylinder gap, which might explain the velocities I was seeing. Throw in the fact that it's a competition revolver that seems to be failing to ignite primers in DA, AGAIN, and I'm about readyu to tell S&W to shove that thing up their ass. Performance Center...………. what a sham. Ok, rant over.
When I tested the same loads in my Henry Lever Action, I got a three shot average of over 1650 ft/sec. That's too fast for that bullet. So My chronograph gave me a little extra info there too.
I am learning I also like to tinker with loads a little too. My recent entry into 38 Super taught me that.
If you do ever buy one, I recommend a Labradar. They are fun to use and seem to give good data. They are pricey though.
However, CraigC is absolutely right. All of that info I got with the exception of the carbine velocity could have been figured out with a little experience, a little reading, and simple deductive logic. Chronographs are fun, and useful, but not necessary.
As far as the trigger thing goes, umm. I guess I'm stupid and don't get it. I don't see how there would be anything but the weakest of correlative data with that, but maybe I'm missing something.