I'll begin by stating I've yet to actually play a game. There are no venues for play in the town I'm in, so I'm mainly just into the modeling aspect. However, a new store is opening soon and is going to carry
40k 
That being said I've been doing a lot of theory craft. One particular issue was whether or not to field 1x unit of 12tau or 2x units of 6 Tau. Even if the units were fielded as 2x 6man, I'd still rlun them fairly close together to serve as a "virtual" 12 man unit. Splitting them seems to give the follow advantages.
(bear in mind point efficiency is not being considered as I'm happy with how they've already been spent. Also, all transports in the army are already claimed)
1. The ability for one of the two peel off if assaulted and set up for a rapid fire counter on the assaulting unit or try to drop back to the main gunline as opposed to the 12man getting locked up in fairly futile combat.
2. 2x shas'ui as opposed to one (giving an extra attack)
3. Unit division, for whatever conceivable reason. (holding an objective, minimizing casualties on one-off attack that target a single unit, etc)
4. 1x additional markerlight. (were fielding a skyray)
As I said, I've got no field experience yet, so I'm looking for some constructive counter points.
Thank you for your time. (pardon any weird spelling errors, I'm typing this on my phone ) ^^;