If I end up running large numbers of fire warriors, I always split them down into MSU now.
With the changes for deployment and going first in chapter approved, I don't feel there is as much pressure to get an army down in as few drops as possible.
Also It means that if you end up in a situation where a squad gets decimated (I.E., it meets wulfen in combat, gets shot on by rubric marines with flamers, inceptor marines drop from the sky) the most models you lose is 5. With a squad of 12, you'll likely see 6-8 die initially then 1 or 2 more running.
If you run 30 fire warriors in 6 five man squads with ethereal and fireblade support, this makes it incredibly easy to make 2 battalion detachments and get 6 easy command points.
The only downside with using lots of small units, and the general downside of tau so far, is playing any mission that uses kill points. All the small units of pathfinders and fire warriors + 2 man drone teams with commanders and stealth teams really add up.
Hope this all helps