Not really ! All tau use pulse rifles because they are good for all types of encounters and enemies, small or big.I don't know if I'd say that the Tau are their peak. That would imply that they are at the pinnacle of how they will develop and have nowhere to go but down. I'd called them a young rising star as a race or an ascending race.
But anyway, I wouldn't say that the Eldar weapons are inferior to the Tau. Yes, they balance things in game to ensure that there aren't a few uber powered races that can dominant the other.
Ultimately when it comes to their weapons, it boils down to how they fight and how they view warfare. The Eldar view war in typical terms, favoring agility and their psychic powers while possessing a diverse lineup of specialists. While the Tau view warfare unlike humans and most of the other races. They see warfare as hunting and it affects every aspect of ground-based warfare for them. Their two philosophies on warfare from which the greater bulk of their strategies are derived, Kauyon and Mont'ka, are both at their core hunting techniques. Which is why they focus on speed and range with their weapons.
It isn't that the Tau pulse rifle is more powerful than its Eldar counterpart, the shuriken catapult, it's just that they are designed and used differently. The pulse rifle is more along the lines of a typical rifle while the shuriken is more like an assault rifle. The pulse rifle can gun down an Eldar before they can fire back but up close an Eldar can pump more shots into a Tau at a faster rate.
Of course that's just talking about their basic guns. I'm not even going to start with the actual tech and the other, more sophisticated weaponry. But a lot of the weaponry of all the races produce similar results through different means regardless of the actual tech involved. Personally, I'd give the actual tech nod to the Eldar.