I really welcome discussion on this topic, however, be nice! Logic, rules as written and courtesy are key – unsubstantiated conjecture on what the author intended, is not terribly helpful. I mostly play in tournaments and “but that's what it’s supposed to mean” doesn’t get you very far!
As I see it, the problem is finding a definition of “Farsight Enclave Army”. It’s pretty important - for example the rules say
“In a Farsight Enclave army, all XV8 Crisis Teams are troops choices instead of elites choices”
This (arguably) is one of the biggest benefits to be gained from the supplement, so knowing when it applies is crucial. The problem arises when you include an allied contingent. The rules say that
In addition to following the Allies Matrix for Codex: Tau Empire, Farsight Enclaves detachments and Codes: Tau Empire detachments may ally together as Battle Brothers”
So the question is – is a list which includes allies a “Farsight Enclave Army”, or is it simply a list with a Farsight Enclave Detachment (whether primary or allied)?
It’s an important question. To use the above example – if a list with Farsight Primary and Tau Codex allies is a “Farsight Enclave Army” then XV8s taken in the Tau Codex Allied Detachment are troops. If a list with a Farsight Primary and Tau Codex allies is not a “Farsight Enclave Army” then XV8s can not be troops, even if taken in the Farsight Enclave Detachment.
A Farsight Enclave Army is defined in the supplement as
“A Farsight Enclave army is chosen using the army list presented in Codex: Tau Empire. It also has a series of supplemental rules (presented below) that can be used in addition to the material found in Codex: Tau Empire.”
So, if you use rules from the Supplement, then you’re using a Farsight Enclave army. The problem is, that really doesn’t answer the question posed above.
On page 109 of the BRB, second column under the heading “Allied Detachment” it says
If you wish your army can include one allied detachment for each primary detachment in your army”
So, “army” is your whole force (to use a neutral term) consisting of both primary and allied detachments. If that’s right, doesn’t that mean a “Farsight Enclave Army” is an army taken entirely from the Farsight Supplement – i.e. with no allied detachments at all?
As mentioned above, the most startling consequence of this is that, if you take any allies at all, your army is not a Farsight Enclave Army. If that’s right, by taking allies, you lose one of the biggest benefits of taking a Farsight list i.e. your XV8s can not be troops.
I really want to be wrong about this, but the wording of the BRB and the Supplement makes it hard to come to any other conclusion.
BTW – I’ve read some of the threads on this on ATT Dakka etc, and they don’t seem to come to a consensus. It may be there is just no answer in RAW and we need an FAQ.
EYIG