Other factors like now the fan spins low on the Witcher 3 compared to stock (joking)
.
But yeah, I know there's always other factors.
Anyway at least in terms of battery I'm sure will make some difference though I haven't tested as I only used it after always portable plugged to the charger.
Temps are probably similar to stock since the fan also spins less and as soon as I press home button from a game the fan starts to spin down almost immediately (off course I have to put my ears on the cooler to hear it).
The downside is the back is hotter but can't say the difference as I didn't use my switch for more than a year and only played now after improving the cooling...