Unique is an excellent powder but often maligned because some reloaders use light loads and call it "dirty" (careful about what you read on line concerning anything reloading related). Almost any powder will burn "dirty" when loaded light, at or below manuals' starting loads. As far as "poor metering" it depends on your powder measure and your methods, and besides when working up a load, weigh every charge. I use Unique, Universal and BR-5 under my 124-125 grain cast and JHP bullets.in some of my 9mm loads
When working up a load, start with powder charges. Start low and for pistol reloading, go up in .3-.4 grain increments. I have found most loads that are accurate in my guns are below book maximums and some work quite well at or near the lower charges. When working up a load I sort brass by headstamps and normally after I find "The Load" I can relax my standards and often just weigh every 4th or 5th powder charge and use mixed brass.
When developing a load, change one thing at a time. My "list" of changes is; First, change/work up powder charges. Then change bullets. then brass preparation and loading methods (crimp, etc.). And lastly, bullet seating depth ("chasing the lands").
I have 3, 9mm pistols and my "Just in Case" load is with a charge of Universal under a RMR JHP. This load works quite well in my 9mms and is more accurate than I am (I keep about 1,000 rounds handy Just in Case). I normally shoot 10-12 rounds minimum when testing a load, and when nearing "The Load" I will often shoot more. I want to find out what the gun and load are doing rather than my marksmanship..
Go slow. Double check everything. Most important, have fun...