Difficulty of Rachmaninoff's 6 Moments Musicaux, Op. 16

[owen212]

Hello!
Recently, I've started listening to Rachmaninoff's 6 Moments Musicaux and I've quickly fallen in love with them. I would love to learn these pieces. If anyone has played or has an idea of the pieces in the set, could you answer these questions: Which pieces should I avoid?  Is No. 6 as difficult as it sounds, or does it just appear to be difficult? Which one is most difficult musically? Should I further familiarize myself with Rachmaninoff's style or is this a good place to start? What is the most difficult aspect of every piece? How would you rank these in technical difficulty?
Thank you. 

[rachmaninoff_forever]

I’ve played all 6.  All of them together in one sitting is pretty gnarly but separately they’re not too bad cause they’re all pretty short pieces.  3 is the easiest and 4 is the hardest.  6 isn’t that bad it fits in the hands pretty comfortably you just put your fingers in the right place and wiggle a bit lol

[owen212]

I see, thank you!

[anacrusis]

Well, I think the fast ones are pretty difficult! At least for me, the Revolutionary Etude by Chopin feels easier than no 4. Though it should be said I have practised the Revolutionary Etude more. 

Musically a challenge with many of them is to keep everything in clearly defined separate layers, else everything blends together and becomes a mess. I feel even some professional recordings seem to forget this.