Alternative dialogue collection?

[Enkidoh]

So wait, when you tell Raubahn to get on his feet because he is a gladiator, was that because I was in the Immortal Flames or something?

It was actually referencing Raubahn's own past as a GLA and Colosseum fighter (he actually owns the GLA's Guild and the Colosseum both, which he won in a high-stakes gladiatorial match before the Calamity in the original version of FFXIV, which is how he got a seat on the Syndicate). The dialogue was merely a way of getting through his funk and melancholia by appealing to his fighter instincts, and had nothing to do with your current class or Job.

As for other alternative dialogue throughout the game, apart from minor dialogue choices which don't seem to really affect gameplay at all, the only real alternative storyline dialogue is if you started ARR as a character created in FFXIV version 1.0 and whom had passed a certain point in 1.0's 'Seventh Umbral Era' storyline (namely, the 'Lunar Transmitter' battle). If you satisfied this requirement, upon starting ARR you got a different opening scene where instead of your character arriving at your starting city on a chocobo carriage or ferry with the merchant and Alphinaud and Alisae, you instead teleported in at the Alythk Deity Stone in Snakemolt like the 'New Beginning' video, and then just walk to your starting city.

That character then has slightly altered dialogue at certain points in the game where ultimately the player is revealed to be one of the original Warriors of Light from the Battle of Carteneau, firstly with Minifila remembering them but then asking them to keep their identity secret for now, then Cid remembers ferrying the player to fight Nael van Darnus in 1.0, and eventually during Operation Archon where the amnesia is lifted from Eorzea and their identity is finally remembered by all and the player is acknowledged from then on as the original Warrior of Light who took down van Darnus prior to the Calamity. This alternate dialogue was only available to 1.0 players who satisfied that above requirement though, and is not available for new players, 1.0 players who started a new character in ARR afresh or a 1.0 character where they did not finish the 1.0 story (my character sadly fits into this later category).

Either way, this is the only example I know of alternate dialogue actually affecting the storyline, but the differences are trivial at best (the patch 3.4 story also has a scene where there is alternate dialogue depending on if you finished the entire Coil raid storyline, but it's again just a few extra lines of dialogue and nothing particularly unique, so most players probably wouldn't even notice.).