Grand Crusader is a great talent on some design levels, but it's odd at others. I'm not writing this from a balance or concerns for raiding. This is going to be about a casual players perspective on the talent and learning to use it - balanced against the depth and skill differences that should exist for someone who wants to learn to play "best." (A summary of the current rotational usages of the talent will follow to help our casual readers of the tank forum looking for information. Skip two paragraphs if you understand current optimal theory crafted rotations.).
In the current iteration with the 3 sec cool down on CS/HotR, Grand Crusader becomes a turning point that helps to separate our single target and AoE rotation. The current models show that for single target rotations we come out ahead by prioritizing Holy Power generation and minimizing loss of global cool downs - to such an extent that Grand Crusader procs are mostly ignored (but not entirely). CS-Judgment-CS-Avenger Shield / Holy Wrath - CS - ShotR. So a Grand crusader proc should only be used if you were about to use Holy Wrath instead.
For AoE, our main abilities are HotR, Consecration, Holy Wrath and Avenger's Shield. Since three out of the four have long cool downs (15-30 secs), Grand Crusader procs are a necessary and balanced part of our ability to put out strong threat (but HotR is strong enough that missing some procs will not kill us).
In the previous iteration where CS and HotR were on a 4.5 second cool down, Grand Crusader was more connected with our single target system. We would want to use it almost every time it procced. There were two down sides to this, 1) a large portion of testers did not enjoy the gaps that could occur in the rotation if procs were not incoming, and 2) there did not feel to be as distinct of differences between the single target and AoE rotation / priority systems.
So . . . here's what I like. I love that the current design does these things: 1) Players who do some research or math are going to play better than others - subjective calls on if the delta is enough are another question. 2) The single target and AoE rotations feel like I'm doing different things and caring about different ways of playing.
Here's what is bothering me. With the release of Blizzard's "Spell Alerts" / Power Auras, GC feels like a trap in single target fights. But I'm not familiar enough with playing many DPS classes to know how common it is for a proc to be a trap. Few other classes are as GCD capped as a Prot Paladin, and this may mitigate how much it matters to other classes. I'm worried though that changes (such as increasing the damaging of AS to make the proc worth using) would rip apart the current design where the two rotations feel more separate than singular.
Can someone post the thread from maintank or ej that ran so many simulations on this? I wanted to check what the difference was between optimal play and a style that attempts to use all procs. Part of evaluating the design would requiring how far from optimal the Spell Alert system pulls you. And I just can't remember that.
As an aside, I did some leveling on beta prior to the 3 second GCD change. I do not think the leveling will help to naturally lead a player to understand that using those procs will decrease the use of wasted cool downs at the top level - so the design fails to lead players to understand how the mechanics mix.