Because, well, bear cavalry

Seriously though, I think this can serve as an update for Rough Riders, or replace them completely, to make them capable of competing with other
FA slots in
AM codex. And also grant the
AM a hard hitting melee unit with some staying power and speed.
What do you think ?
Fluff: The Maulers are composed of the strongest and most hardy Valhallan their world can provide. Riding the genetically-modified Valhallan Polar Bears, the Maulers crash into enemy battle line with unstoppable force, mauling and trampling their foes under their mounts's feet. The bears also provide their riders the ability to cross water, allow the Maulers to launch their attack from unguarded enemy flanks. Valhalla Maulers - Fast Attack - 125 points Mauler WS3 BS3 S4 T4 W2 I3 A2 Ld7 Sv4+
Mauler Sergeant: WS3 BS3 S4 T4 W2 I3 A3 Ld8 Sv4+
Unit Type: Cavalry, The Mauler Sergeant is Cavalry (Character)
Unit Composition: 4 Maulers, 1 Mauler Sergeant
Wargear: Carapace Armour, Laspistol, Close combat weapon, Hunting lance, Frag grenades, Krak grenades.
Special Rules: Amphibious, Rage, Rampage,
Trample Trample: A model with this rule inflicts one automatic hit for each enemy model in base contact with it, resolved at the model’s unmodified Strength,
AP -, at the Initiative 1 step. This does not grant the model an additional Pile In move at the Initiative 1 step.
Options:
May include up to five additional Maulers: 25 pts/model
The Mauler Sergeant may take melta bombs: 5 pts
The Mauler Sergeant may exchange his laspistol and/or close combat weapon for one of the following:
- Bolt pistol: 2 pts
- Plasma pistol: 10 pts
- Power sword: 10 points
- Power maul: 10 pts
One Mauler may carry a vox caster: 5 pts
Up to two other Maulers may replace their laspistols with one of the following:
- Flamer: 5 pts/model
- Grenadier gauntlet: 5 pts/model
- Meltagun: 10 pts/model
The entire unit may take slabshield: 15pts/model