The best comparison for gated vs non-gated is NP and NP Square.
As much as I hate to admit it, folks drive through NP Square as a pass thru from Irvine to Culver (or Bryan to Irvine) to avoid a couple of lights.
More folks utilize Bunny Park in NP Square than any of the parks in NP.
There are more cars zooming around NP Square than NP, and that makes it feel less intimate, slightly more stress-inducing.
NP's entrances are designed such that you cant easily park and walk - you'll be walking quite a ways to access NP if you arrive via unregistered car. So that diminishes public use of NP's parks and open space by "outsiders," and encourages walking within the community. It's one of the reasons there are tons of walkers in NP (aside from the paths and lush landscaping).
Interestingly, the HOA difference between the 2 communities is minimal - $40 or so per month - and the amenities you get for that $40 are sizeable (tennis courts, more pools, guard gate).
It pains me to write this because I prefer NP Square to NP - it has slightly easier access to shopping and the gate, while nice in diminishing traffic, is silly as a protectionary measure (false sense). And it projects a tacky image of exclusion and separation. Given we ended up in NP, you can tell who won the argument