Each expansion up to this point has been a gear reset.
As in, unlike Everquest I, there is nothing you have equipped at 80th, which is still worth equipping when compared to level 85 heroic/raid drops.

If each of the teams you care to level are 80th at the release of Cataclysm, they're on equal footing whether they dinged 80th the day before release or have been there for over a year... well gear might make the initial zones a bit easier, but they're balanced for single toons, while we run groups and absolutely slaughter the early content.

I'm pretty much very casually adding alchemists to my mix, purely for gold. Have not really logged in to play, aside from transmutes (existing alchemists) in about three weeks. I'd ideally like to level the teams upwards a bit from 68th (minimum for 450 skill is 65th, but transmute specialization is 68th) towards seventy-something, as the minimum level to reach maximum skill will likely increase a bit.

But at this stage, its pretty much just getting toons/teams ready for Cataclysm.