I don't remember anything refuting it either. There are only two people on BG who I look to when I want to understand BLU, and one of them supported my view point by stating that there's probably a reason all physical BLU multiplying markers are at 0, 150, and 300 instead of 100, 200, and 300. It wasn't certain, but it's no less reasonable than anything else. I didn't post that as proof that I'm right, I posted that as proof that I question the usefulness of Enchainment before 100%.
The fTP span on Cannonball from 0 to 150% is .375. Divide that by 15 and you get 0.025 for every 10 TP, assuming that the growth rate is constant and that it begins at 1. Both are unknown. If both are true, yea +0.015 is an extremely significant amount over my approximation referencing no particular spell. -_-
Blu isn't just CB, even in end game. Even if it were, doubling stat mods DOES contribute more than a ~7% increase to the multiplier. Does that make 1 or 2 or 3 stats more powerful? No, but if you didn't whore as many stats as possible, you wouldn't have as much to double and then you wouldn't have as much to multiply.
Don't get me wrong, CB is a significant boost when you're holding back spells for 2 minutes (Pro-tip: A BLU doesn't need to spam spells to still hemorrhage MP. If you're not using them at a decent clip, it's either because you can't or wont, not necessarily because you shouldn't.) However, in any other situation, it's not going to be affecting most of the spells you use. An additional spell or a spell upgrade, on the other hand, can completely change what you're able to do and how well you're able to do it without being restricted to a JA. That is how 1 set point is superior to Enchainment.
Frankly, CA has become a lot like Focus/Dodge on MNK to me. They're powerful, but it wont improve a good player's performance unless it's under special circumstances (CA + CB, Focus + 2H). I don't purposefully not use them, I just forget. If I notice that I need them, I realize I have bigger problems than a lapse in memory.