Having played 8+ games using the new tau codex with some of the new units proxied. I can confidently say that the largest improvement on the codex has come from the new markerlight rules. (Well, and ShadowSun. Tau have finally joined the ranks of 40k armies who don't give a flip about Leadership, more on this later though.)
If you utilize full squads, small numbers of markerlight hits on a target can be absolutely amazing. Exploring ways to 'sprinkle' markerlights through your army is definitely worthwhile. Take the instance of a standard FoF attack:
12 Firewarriors rapidfiring
Unassisted vs. T4: 8 wounds (24 * .5 * .66)
1 markerlight vs. T4: 10 wounds (24 * .66 * .66)
2 markerlight vs. T4: 13 Wounds (24 * .83 * .66)
To match the effect of the 2 markerlight hits, you would have needed an additional 15 shots ((13 - 8) / .66 / .5) or 75 points worth of firewarriors. By no coincidence 75 points is about what you can expect to pay for 2 markerlight hits (we'll get into it later), so where's the advantage? Versatility. Markerlights can essentially provide the same effect as adding more units to any given engagement.
Second example for a 'Mugger' Suit configuration I'm becoming fond of (in conjunction with markers).
3 XV8's, each with Plasma, Fusion, Multitrack
Unassisted vs. T4: 3.8 wounds (9 * .5 * .833)
1 markerlight vs. T4: 5 wounds (9 * .666 * .833)
2 markerlight vs. T4: 6.3 wounds (9 * .833 * .833)
With a difference of 2.5 between unassisted and 2 markerlights, you're looking at adding 4.5 more shot ((6.3-3.8) / .833 / .666) or 1.5 suits at 62 points each. 91 points worth of shooting for 2 markerlight hits, neat.
There are less tangible uses as well, such as removing cover saves, firing the occasional seeker, and really loading up markerlight hits to reduce Ld vs. a non-fearless opponent. Excess ML hits can always accomplish something. I count these as icing on an already great tasting cake.
So if you're sold on markers, lets investigate the various options available for including them in a Tau list:
1 - Marker Drones: Attachable to XV8, XV15-XV25, XV88, Firewarrior, and Pathfinder squads - Pathfinders get markerlights cheaper, and XV suits would have to sacrifice their movement to use them (not impossible to use, just less practical). Stand and fire XV88's could find a good use for them mixed within shield drones, though they are already an enormous fire magnet. Leaving us with: firewarriors - a typical squad will pay 80 points for 3 BS3 marker shots, Shas'ui upgrade, markerlight, 2 Markerdrones. This works out to 53 points per marker hit average (80 / (3 * .5)). With a lot of ablative wounds and a platform that does a lot of Standing around shooting, this is a pretty good option. The downside being the frugal value of a firewarrior wound is being blown out of the water, making shots directed at the squad significantly more worthwhile. -Decent longevity, below average cost per ML hit-
2 - Sniper teams: 80 points gives you 3 TL Rail rifles BS3 and 1 BS4! markerlight, all sitting pretty with a stealth field generator. If you were to subtract the value of the BS3 Rail rifles using the Pathfinder w/railrifle equivalent (22 points each) you are left with a 14 point BS4 markerlight with a stealth field (sweeet!). This is approximately 21 points per ML hit (14 / .66). Obvious downside here is that you can only field 3 of these guys, they are stationary, they do not hold quarters or objectives, and they suck up a heavy slot. There's a lot of good, and a lot of bad in them. I highly suggest proxying the 3 units for a few games to see if you like the feel of it (3 gundrones and a pathfinder?). -Good longevity and field of fire, poor choice for objective purposes-
3 - Pathfinders: As the Devilfish has become a great deal more beefy with the SMS option, I am going to leave it out for the cost comparison with pathfinders. I feel that a 120 fish is currently worth every point you spend on it, especially with the crazy deepstrike bonus yield from the pathfinder specific fish. Pathfinders at 12 points are the bargain unit, and the ultimate resource for making sure the target gets enough markers on it to finish the job. At 12 points for a BS3 light, 24 points on average will buy a ML hit. Their downside is that they tend to over-do it and markers will undoubtedly be wasted eventually. They are also quite fragile and very high on the target priority list against most opponents. Because of this they tend to be less flexible than the other methods since they simply cannot last long enough in a position to pick and choose marker-targets, a restricted line of fire will give them some longevity at the cost of target selection. -Excellent cost per ML hit, low survivability-
4 - Skyray: The perfect option for getting a few markers where and when you need them. It's difficult to extract the exact cost you are paying for the markers on this vehicle, as there's a lot of options to account for. Largely the loss of a Railgun or Ioncannon is the primary concern, but considering the above examples: sometimes an augmentation of another units firepower can be more valuable than even a railgun shot. If you plan on sprinkling with markerlights through your army, 6 seekers will prove an invaluable asset as well. -Excellent maneuvering and additional benefits, poor cost ratio-
5 - XV15's: Covered somewhat by Markerdrones, I feel this is a pretty solid option if you are dead-set on a mechanized list. Take 3-4 stealth suits, purchase the team leader and markerlight upgrade. Give the team leader a targetting array (a fusion blaster is a good fit too), give the remaining members drone controllers and 2 marker drones each. For a 3 man squad this costs you 237 points and provides you with an average of 2.66 markerlight hits (1 BS4, 4 BS3 shots). Average cost of 89 points per marker-hit, but they are quite versatile with infiltrate, stealth fields, and a 6" assault move. The team resumes normal XV15 activity once the targets close to 18". -Good longevity and field of fire, expensive point to ML hit ratio-
I will leave the direct cost-benefit comparisons to the individual player as it will likely vary greatly from mechanized to static to mixed. Know this, the markerlight is always your friend.
Anyone else reaching these conclusions with new Tau? People around here are really starting to grumble about facing the new MLs.
