It's time for a retrospective and an early prospective on how the Greater
W...Good is faring in the new edition of forty thousand shots. So sit down and strap in because this will be a multi-parter.
The BRB changed the rules for regrouping and placed an emphasis on sergeants and other 'characters' within an army, so it's time to look at the Tau sergeants. Be aware that a fire warrior shas'ui team leader or a battlesuit shas'vre is considered a character, but a battlesuit team leader is not considered a character unless (s)he is a shas'vre. Only characters can accept challenges, but remember this is Tau, the one race in the game that views melee combat as barbaric and would not seek to prove themselves in melee combat. Challenges can only be issued if there is a character in the opposing squad (p. 64), so no challenges can be made against battlesuits that do not have an IC or a shas'vre or against fire warriors without a shas'ui. Some may say that this is a bad thing because the potential challenger can run rampant in the opposing squad, but again this is Tau we do things differently. In the case of fire warriors, it is definitely preferable to allow the team, if engaged in melee combat, to be killed wholly rather than risk it staying in close combat and dying during your turn while protecting their killers from shooting.
***DANGER: Probability ahead***The shas'ui does bring a welcome leadership buff, but even then only raises them to the level of marines without a sergeant (ld 8), for a 17% increase in points cost. While leadership seven is poor compared to other units' leadership, it is both probable to succeed (58.34%) and the point of diminishing returns for leadership. The probability of rolling a seven on 2d6 is 0.1667, while that of rolling a six or eight is 0.1389, five or nine 0.1111 and four or ten is 0.0833. Therefore, the value of each additional point of leadership increases up to seven and decreases afterwards, so the value of the leadership buff from a shas'ui is greater than that of a marine sergeant for the same price, but the value of the marine's extra attack is much greater than that of the shas'ui so it balances out. As far as the question of is the shas'ui a worthwhile purchase, excluding his extra attack and obligation to accept challenges (which you don't want to), we need to compare the increase in price and leadership. At leadership seven the fire warriors pass 58.34% of their morale tests while at leadership eight they pass 72.23%, an increase of 23.81% and a melee damage *lol* output increase of 16.67%. In two aspects, neither of which are particularly necessary, yes, the upgrage to a shas'ui is worth it's points. However, if you want more firepower, you could get a 16.67% increase for the same price. Note that the points efficiency of the leadership increases and the extra attack increase and decrease respectively in proportion to the increase in the fire warrior team's increase in size. So at a full team the leadership buff is still a 23.81% increase, but the additional cost is only an 8.33% increase, while the melee attack is an 8.33% rather than a 16.67%.
Now let's look at arguably the most iconic piece of tau wargear, and the most common on shas'ui team leaders, the bonding knife. The entry was changed by the 6th edition FAQ to read "A unit that contains one or more models equipped with bonding knives can always attempt to regroup using its unmodified leadership value." Because the shas'ui or an attached IC are the only models that have access to bonding knives, the team will be testing at no less than leadership eight. Assuming the team is operating without an independent character we can calculate the effectiveness of this piece of wargear. In the BRB, units attempting to regroup may do so at their normal leadership unless it has fewer than 25% of its original models remaining (p. 31). If it has fewer than 25% remaining, it must roll insane heroism to regroup. For a maximum size team to qualify for testing at insane heroism it must have two or fewer models remaining. For the bonding knife to be effective, one of these models must be the shas'ui team leader. The bonding knife would increase the probability of passing this test by 2099% when compared to a team without a bonding in the same situation. Not bad for five points ;). However, the bonding knife is only available if the team already has a shas'ui, so to acquire one the cost from is closer to fifteen points, as the shas'ui provides no benefit beyond access to the knife under the circumstances in which the bonding knife is effective. The bonding knife's cost would only benefit two models, so it would increase the cost of the reduced "team" to thirty-five points rather than twenty. It is only an increase of 75% cost to massively increase the probability of saving that unit. The question comes down to whether the probability of recovering two fire warriors is worth the additional cost of the bonding knife and how likely it is that the squad will be reduced to two models or the shas'ui, but not wiped out. For me it is a small enough chance that I would not.
Not sure what I'll talk about next, but I hope you prosper as T'au shall.