Flat hopping is definitely one of the easier hop up modifications.
It's a good mod to start out with, and if you ever end up R-hopping, your bucking will already be good for it.
I have had minimal experience with moundless buckings, and what I have played with, wasnt all too great. Fitment and airseal issues. Was with some grey bucking, I don't remember the brand.
I've found great success with G&G green buckings.
I would say it's performance is better than stock(I'm sure many others will agree), so it is worth doing.
And I wouldn't bother with premade nubs either; pink eraser works just fine with a little bit of custom fitting.