You can be a heavy rp'er without being constantly IC. It's true that in the good old days, being always-IC was one of the big trademarks of heavy RP'ers, but that sort of stance doesn't always mesh well with the given settings/lore of MMORPG's. In FFXIV, there's a big complex with that there is only one Warrior of Light, so all of the quests you do as that person, it becomes hard to be IC through them (Not that there aren't people who try, mind) because you may end up meeting someone else who also claims to be the Warrior of Light. One of the other big marks of a heavy roleplayer is their lore adherence - so there would be a conflict of interest there. In the end there isn't any wrong or right, however I think that Eva did a very good job at explaining it in The Roleplay Handbook. What I would encourage though, if you want to pick a label for yourself (You don't have to!) is to be honest with yourself. If you feel like you're more light, there's no shame in saying that, it'll help you meet like-minded people. I think this is also why many people end up putting themselves as medium - a good flexible mix of the two ends.
