I think I will disagree with chakax not been as great as worth 300 pts.
As a bodyguard he just owns. Period. Actually I can't Recall a single character, exept a Greater Deamon and other 3W+, that would have the odds with him. Havn't read his rules yet, but from what I see on the site I recon he gets a ward save as well as enemy weapons count as mundane weapons, and that takes away the most offensive enemies cons(assasins and a hard hitting characters e.c.)
You will field him in a unit of Temple Guard anyway(That may be your only choise, don't if there is such a rule..)
And as he is protected by the numbers of his fellow temple brothers, he cant be targeted exept by a challenge. Thats where you whant him anyway so no prob there.
As the temple guard is such a tough unit and seldom runs, you got yourself a magical powercenter in you slann, your temple guards watch his flanks and keep the enemy from reaching him pluss dishing out a lot of carnage them selves. And to top it, Chakax will end any character who tries to break through to your general.
The only downside with this unit is that you'll suffer from the "all eggs in a basket" syndrom, and since you'll be moving slow, the best counter your enemy can throw at you is to refuse to get in CC with this unit. If that happens, it's a lot of pts wasted and a tactical loss for the lizzies, so be sure to deploy and manouver good in the critical 2 first turns.
As for a scar-vet to be as good: a scar-vet can easily be taken out if he get charged wich he most oftens will be in a TG unit... Chakax simply will survive more charges as he strikes first and nerfs his opponent as he refuse him in using magical weapons.
In my opinion there is little doubt Chakax is a Badass chalanger and survivor, so it realy boils down to whether his worth the pts cost.
Pros: You almost as good as assure your unit against dangerous enemy characters
He hits first and when fighting enemy rankandfile units, you can take out some of his attacker, witch in turn gives your TGs more counterattacks which gives you an edge when it comes to Combat Result.
(and is it right he reveal enemy hidden characters as fanatics and asassins within 24"? if so, that is a huge bonus.)
Cons: He takes up a good amount of pts and since he will join a slann(if you has any), you will have a lot of pts on a single spot --> easy to out manouver...
Sum: If you plan right, and compose you army right, I think Chakax is a great addition to our range of characters, and surely he will make an approch in some of my armies at least some of thouse with higher pts limit.