I'd agree with this. It's why i bought 3 new TM NGRSs, changed the barrels and hop rubbers and called it good.
They have accessories on the outside, nothing else changed inside. The guns' performance far exceeds my shooting ability.
I agree with this too. And if you're buying your first gun i'd say it's safe to assume you're not going to be well-versed in teching so really you want something pretty reliable. Yes, brand new guns can fail too, but that's probably less likely than one that's been messed with.