Arming the Crisis Suit, post FAQ
So with the latest wave of FAQ's, the Tau Crisis Suit is now able to be armed with multiples of the same, non-twin-linked weapon (I love to say I told you so). With that said, where does that leave some of our older suits, and what does that mean for the future of Crisis Suits?
Fireknife Crisis Suit
The classic Fireknife configuration was the staple of many Tau armies for a long time. In the distant past, you couldn't equip a Crisis Suit with two of the same weapon, so instead you had to diversify, which lead to a S6 Plasma Rifle coupled up with the S7 Missile Pod. This lead to the premiere MEQ killer, as well as the ability to take out light vehicles. Now though, you could take 2 Missile Pods, or 2 Plasma Rifles for the exact same cost, so what does that mean for the Fireknife? Sadly, I think this configuration is going to slowly go the way of the dodo. It's not terrible, and there's something to be said about the versatility (and increased kill zone) that the Missile Pod offers, but I think you'll instead see people pay the same points for double plasma, or even double missile pods.
Helios Crisis Suit
Another classic, this suit is a combination of Plasma and Melta. It was previously a method to maximize anti-marine fire power, granting 3 marine killing shots within 12", as well as the versatility of killing heavy armor. With the increased range of the Fusion Blaster, now this suit can kill 1 marine at 24", 2 at 18" and 3 at 12", which is definitely not bad! Double plasma might out-shine this suit over 18" and under 12" with an extra shot, but it wont be able to handle heavy armour. This suit might actually be killy and versatile enough to survive the 3rd expansion.
Sunforge Crisis Suit
This suit wasn't hugely popular before, but not unheard of, it has had several buffs this edition though. First of all, now it can have 2 Fusion Blasters, instead of a single twin-linked one, plus you can still give them each a target lock for pulverizing as many tanks as possible. Additionally, the increased range means they wont need to get so close to kill tanks, Thrusting after you initially shoot means you'll end up on average 16" away from a target after you shoot it (within Melta range), so you don't have much to worry about retaliation. In the end, a fairly solid suit if you ask me.
Deathrain Crisis Suit
Similar to the Sunforge, it now has the added bonus of a built-in multi-tracker, meaning you can forgo twin-linking for a second missile pod instead, plus you'll still have another system left over for vectored retrothrusters, shield generators or whatever suits your fancy. At 156 for a squad of 3, you're effectively getting 6 autocannons, which isn't bad compared to 115 for 4 Chaos Havocs with 4 autocannons, or other similarly equipped units. Like the Sunforge, having non-twin-linked weaponry really is helping this configuration out.
Heatwave Crisis Suit
This is a configuration that i've always thought looked cool, but frankly was awful before. In 6th edition, I think I might give these guys a try though! 2 Flamers plus Vectored Retrothrusters or an additional ranged weapon can really be devastating, imagine this: 3 double flamer suits, move up to the enemy, unleash 6 templates, then assault back, you get charged and you overwatch 6D3 more hits, then Hit and Run (get some drones for I4 H&R), then you do it all again, flame, overwatch, flee. Also, they can sit behind a unit and contribute a ton of hits from Supporting Fire! On top of all that, they're only 37 points! I think I'm in love.
Burningeye Crisis Suit
This is the configuration I expect to see everywhere now. 2 Plasma Rifles means you're going to annihilate marines, 2 at a time from 24" and 4 at a time within 12". If you really want to make this unit shine, you could put in a commander with Command and Control module to twin-link all their weapons, or even take an O'Shova Bodyguard laden with these guys. Throw on Advanced Targeting Systems and now your suits are popping heavy/special weapons all over the place, and maybe even a few sergeants or characters. They are a fairly expensive configuration, but with all the MEQ in the game, they'll surely be popular.