Regarding their offensive outlet, I think PF fixed the problem with their "always hit on 4's" WS.
I wouldn't change anything here.......guys, its S7 ... if we cant see ourselves satisfied with that, then we might as well give up.
Where I WOULD change things, is in movement, resilience and/or Static Combat Res.
If not an entire command group, for the love of Quetzl, give krox a Musician.
Krox blocks are close to useless against fast/chaff armies, and a musician could really sooth up the "These guys work best in big blocks" vs "These guys are terrible to maneuver in big blocks" problem.
Adding a banner would also really add something to it.
If they ever got full command, I would play two blocks of 3x3 each and every game

(yes...I have the models....dusty poor bastards :'I )
Last and final: If my krox wouldn't just die before they got to do anything, I wouldn't mind anything above as much...
Everything worth fighting with them, doesn't care for AS 4 or T4 .. and since it most certainly hits on on 3's that T4 gets even more laughable.
Confession: it helps A LOT vs BS armies, as they shrug of most arrows because of this...that IS nice, but it is not enough.
I really think krox need bigger resilience to work.
I think T5 is overkill combined with S7. You would basically get a mundane Scar vet, close to a cowboy, for 25ss.
What I would do if it was me, I would indeed give them tougher Scaly Skin.
They ARE crocodiles, and those scales are NOT for butter knives.
"Crocodilian Armor". (I know it sounds corny, but its an actual name)
When calculating a Kroxigors armor save, half and round down inflicted armor save modifiers.
Treat Special rules as Armour Piercing the same way, but "No armour save" is not affected.
S4 = -0
S5 = -1
S6 = - 1
S7 = - 2
Its worse than a ward, better than regular armor, and it can still be dealt with.
It means that our krox' would rock a 5+ most of the time, which is actually quite good taking their W value into perspective, and RARELY stand back with less than a 6+.
This way I would pay 25ss any day! but as it is I think other armies gets WAY more bang for the buck.
I would say 20ss would be far more fair.