Not talking about procs from a BLM; I'm aware that using them on a BLM runs a risk of not only a DPS loss, but can result in a loss of Enochian if you're not paying attention.
Also, a BLM's casts line up with their cooldowns, unlike a BRD, but having more potencies and buffs to increase their damage. BLM has never wanted for damage, but BRD has generally been on the lower end of the stick in terms of DPS.
Right, because a comparison for an entire class is valid against your longest cast that you use only when you have swiftcast and convert on a single target. You're also not taking into an account for when the server tick is, otherwise you run into stutter stepping still interrupting your cast on a BRD. A BLM's cast times are high enough that you probably won't run into that issue, but to say it won't happen is folly, as is to completely ignore that simple fact.