Ok, here are the numbers I got, based on 20 fireball samples and their dps, crit rate, and time to complete:

Alternating castsequence macro:

Code:
/castsequence Fireball,,
/castsequence , Fireball,
DPS Crit Time
820 4/20 1:03
956 8/20 1:03
954 7/20 1:04

pure /cast

773 3/20 1:03
921 6/20 1:03
843 6/20 1:03


/castsequence fireball, fireball, etc

984 10/20 1:09
967 9/20 1:08
957 9/20 1:08
676 2/20 1:07



Castsequence came out with the generally higher dps, but I blame this on my stupid freaking crit streaks when I got to that point in testing. It was still taking an extra 4-6 seconds to get the same number of casts in. Take that as you will. Good news is the alternating castsequence macro works. And now I have to actually get back to work. Be abck later.