I have no experience with a Lee Auto Drum. That said, in my RCBS Uniflow (the only powder hopper I've ever used), Unique can throw a little more wonky than many other propellants, but I can't hardly imagine it being a "show stopper" issue for a beginner loader with an auto drum. Just start low - as usual.
Aside from the fact that I wouldn't trade a # of W231 for 8 #'s of Unique
, I believe Unique is a rather good choice for a beginner handgun loader.
Unique is considerably slower than W231 and thus, affords more forgiveness. It also has a good fluffy fill rate. Lighter bullets also affords more forgiveness btw; and so starting with 115's (9mm) and 110's/125's (38's) might be a good idea. (By dumb luck, I started with light bullets back in '84 and it probably spared me a gun and a couple fingers.)
Either way, the 9mm part is a little concerning as I wouldn't recommend starting with them. I'd crank out a hundred or two of 38's before moving to 9's - just my two cents.
At any rate, I think Unique is a good starting propellant. If the powder throw thing remains a lingering issue, consider HS-6. It's about the same burn rate as Unique (a little slower, actually), and is a very predictable, cool running (low energy),
smooth metering, forgiving propellant. HS-6 runs sooty when underloaded - but that's a concern for the more advanced loader. A little soot and grainy residue is just fine for the novice.