To add a little more to this. I think RTA at all for this game will get kinda boring. It will quickly be, just to see who can get to each dialog block faster. There are ways to shave time off of this in IGT, but not RTA. Routing for RTA is easy peasy, routing for IGT is much, MUCH more tricky

DLC matters a LOT. Faster mounts, different, and better Magic Weapons, etc. DLC makes a difference, for sure, no doubt about it.

IGT is good for NG+, where all menuing is kinda pointless. In NG, it matters a ton more, as you need to check weapons, use GP's, do camp upgrades, pick support teams, etc. But in NG+... It doesn't really matter, sense it just means who can skip scenes faster