I don't keep the laptop plugged in because I fear the charger will be incapable of charging the battery while powering the computer under gaming conditions.
That sounds like an awful reason not to plug your laptop in.
Let痴 suppose that your laptop
is using 85W (the max your power adapter can provide) at all time during your play sessions. Then:
- Given that your battery is 77.5Wh, you won稚 be able to play on battery even for one hour at a time. No miracle there.
- Worst case scenario, your SMC is providing all available power to the circuits and not charging the battery. Leaving a battery untouched is not an issue as long as it is not for weeks or months.
In any case, I would expect
decreased battery life when using your discrete CPU over the integrated one.