Personally, I'm sticking to 4 Ns.
Mainly because I play Volcanion, and have Oranguru, so getting down to 2s and 1s is not an issue.
But there are two other reasons I prefer 4 N:
- N is arguably the best supporter for late game, because it allows multiple options.
Late game, you don't want to play Sycamore, or you risk milling yourself and/or losing your remaining resources.
Cynthia does not differ much here, which is the issue.
N is great, because it allows a "safe" draw option.
N will only be drawing you around 4 cards mid-to late game, and can actually be used to prevent a deck out; while simultaneously changing your opponents hand.
Now this can be a good or bad thing, as we know... but, it leads me to my next reason.
If you are running a 2-2 split, you just... have less Ns. There's no way around that.
That means, if you find yourself with a bad hand, and
have to N... You now only have 1 N for the rest of the game; which could be prized...!
This means, you have less of a chance to react to/disrupt your opponent's plays.
Examples:
Sylveon GX card search, A-Vulpix Pokemon search, and Drampa GX's Big Wheel.
So, even if you're running Lusamine, you'd have to get the N back ahead of time, to be able to play it.
More options allows you to make better plays. N allows more options; especially since it has the same use as Cynthia at the start.
Reasons Cynthia would see play...?
Well, it's not a bad draw supporter, at all.
So, if you're just looking for more card draw, then... why not?
It is also preference in the end, I was just explaining mine~
Sycamore will still see play.
While it sucks to throw away cards, it's also a good thing.
Shuffling is less effective at "finding" a card, as you're putting the cards you don't need back into the deck.
Example:
You need a DCE to win, you have 7 cards left in your deck...
Sycamore guarantees the win.
Cynthia will not.
Sycamore's also used to get cards into the discard, that want to be there.
Examples:
Night March or Energy for acceleration (Volcanion, Darkrai, etc.)
Also... just drawing 7 over 6, could be the difference in a match.
Most deck lists are running:
4 Sycamore
4 N
3-4 Guzma (with 4 being more common)
Though, you're probably right on the second part; people will likely sub out a supporter for Cynthia.
Maybe go down to 3 Sycamore, or 3 N.
However, I don't see her outright replacing either~