As discussed in the previous video below (with the exception of Off Balance being exclusive to Stamina DPS as Magicka DPS now have more free Champion Points due to different allocations) and also touched upon in our guide regarding Concussion, Off Balance, Charged and Shock enchants, nothing has changed in the decision making you have to do as a tank when deciding on equipping a back-bar Lightning or Ice Staff in raids.
So long as Concussion uptimes are taken care of by at least two supports (Charged, Shock enchants) and that there's a minimum of two Lightning Walls for the Off Balance uptimes, then it's typically free-form there unless there's still issues with Off Balance uptimes as Off Balance is a huge bonus to the group's DPS.
For 4 man content, it is likely that unless you're playing extra safe for places like Veteran Blackrose Prison where the post-Markarth Ice Staff has proven quite effective for the high-damage projectiles, you will still go Lightning Staff as a tank.
If you are optimizing raid compositions, it is highly unlikely that you will place the responsibility of maintaining Minor Brittle uptimes (which directly correlate with Chilled uptimes due to how Minor Brittle works) onto the tanks or DPS unless you don't mind the DPS loss.
It is still debatable as to whether tanks should be running double Ice Staves but it may depend on content and setup. However most likely, most of the time, it will go to the off-healer whether they're in Martial Knowledge/Z'en's Redress/Elemental Catalyst/etc depending on the composition.
Tri Focus remains something most tanks would typically not put points into should they be using a Frost Staff as it can heavily affect their Magicka sustain which can prove often critical depending on fights.
Recommend for putting points into this passive if using Lightning Staff.
Casting a Blockade of Frost (for Crusher uptime) will give you and up to 5 other nearby allies a Frost Safeguard shield which is very visible in terms of visual appearance. This shield only absorbs projectile damage which is quite perfect for various fights or places such as Veteran Blackrose Prison, Veteran Cloudrest, Veteran Sunspire Lokkestiiz and so forth.
Even if you don't put points into Tri Focus, you will still get benefits from Ancient Knowledge which still gives you block cost reduction and mitigation on an Ice Staff.
Quite interestingly the 1800 Magicka restoration that occurs every 10 seconds also happens to other people should they be shielded by Frost Safeguard and also absorb projectile damage from Blockade of Frost!