The new ranks of debuffs in TBC are bugged and will not be prioritized as they did post-TBC. Use the vanilla rank of CoS and CoE and they should stick until they time out.

I would recommend having a few people start threads about this on the official forums, to ensure blizzard puts some effort into correcting this issue.
It would improve raid dps by a fair margin i think ?


Before shouting at me further, that post you replied to was made (09/07/07) before 2.3 which was released at 13 November 2007, about a month later. Neither me, or anyone else here is clairvoyant, so... what gives ?

Also, we had two fire and two arcane mages in the guild at our last Kael attempt, and they're all still producing good dps. There certainly isn't any major conviction about which spec is better in specific situations.
If threat is an issue, then arcane can still perform quite well, as long as you got a shadowpriest to back up your mana consumption.
This is at the TK/SSC level though, it might change when we reach Hyjal.

I was under the impression that AM was already confirmed to have a hidden debuff while channeled, and that it was no longer speculation.

Not to resurface this, but since I didn't see it confirmed: yes, it's a flat 15dmg redux.