The interesting comparison would instead be; what if you brought along a second barbarian instead of the alchemist? Or, what if you buffed the group's fighter instead of yourself?
Party dynamics are hard to work out; trying to work out "who does the most damage" is then pretty tricky. If the fighter does 90 points fo damage on the critical, do you credit them with 45 points, and split the rest between the bard and the cleric who buffed them? I probably could do that sort of analysis, but it should be pretty clear that the people doing the buffing are going to get a lot from this. The alchemist will too, giving CA pretty regularly. So I've stuck with the simpler analysis, which clearly favors the barbarian, so as not to inflate the "pro-cleric" numbers.
Barbarians are great for single melee opponents; having two would be overkill. Swapping a cleric out would be terrible, as we need the in-combat healing and the barbarian needs at least 2x as much as anyone else. Alchemist is probably the weakest class in the game, so swapping anything out for it would make a "more efficient party". But a wizard would be better than another barbarian. We've had most difficulty with opponents at range or teleporting at will, or flying, so no real reason for a second "solo guy in a small room" specialist.
I've just multiclassed champion with my cleric, which adds some nice damage mitigation and melee reacts. Probably a full champion would be the best current addition to our group.
My cleric also can summon choir angels, which is another excellent source of damage for parties without a bard. One action a round to have the angel increase party damage by 10% (and also have a small chance of doing minor damage) is pretty nice.
One of the reasons I like the balance in PF2 is because it really does feel that most classes pull their weight and are needed regularly. Alchemist, in my experience, though, might be the exception. It only really shines for groups of high-AC characters.