I would never want to be in 49's with less than 2k HP as a twink. You're rogue bait at that point and will lose 50-60% of your health with an AIM shot crit. You're only a glass cannon if you can survive being jumped. You can't do that with fire.
Frost mages can be incredibly difficult to fight. I can't imagine doing this bracket as anything but frost unless you have a pocket healer.
That Chardev link has questionable items IMHO. I'd rather take an Arbiter's Blade with Soulfrost as my main hand. Only reason to that, Felbane Sword with 63 spell power, is if you want to dual spec and alternate between fire and frost without paying for 2 high level TBC enchants. Of course, you can always get two Arbiter's Blades and do one with Sunfire another with Soulfrost. That's probably what I'd do if I wanted to test fire and frost.
I also think there's better options for the chest piece but that's just an opinion. 49's have no real clear cut BIS for cloth chests. The BOA is probably the strongest option, Grimlok's Tribal Vestments are good, Chan's Imperial Robes are good, Funeral Pyre Vestments are good, Nature's Embrace is not horrible. I always hated the fact that Robes of Winter Might were just out of range of 49's. I wanted those so badly when leveling but never got the damn recipe to drop.
I don't know anything about mages, one of 2-3 classes I never leveled/played. All my experience was with locks and priests. So that being said I can only say I know what I hated playing against and that's frost. Except on my lock of course then mages were LOL HK.