Congrats on your umnum, I think that you're going to love it! I know that I do mine.
I pulled it apart when I bought it to remove the lanyard, while it was apart I cleaned it ( even though it was still clean ) and used a bit of the CRK fluorinated grease ( I use it on all of my CRK's ). It's been almost two years of edc use, and I use my knives, it's still fine although I'm sure that it deserves a regrease. I doubt many other oils could claim that track record. As far as how quickly it opens, well, I can flick it open with one hand without issue, not as fast as an axis lock but it wasn't designed to be, still lightning quick though.
It's worth the 15 to get the grease, if you clean your umnum a lot it'll still last you many many years, a little truly does go a LONG way.
Congrats again on getting one of the best folding knives ever designed.