Spam with a side of Grav ... WIP White Scars List

Warhammer 40,000 – There a silly random team event coming up in my area that has some strange limitations. I'm using it as motivation to get some of my own models painted as nothing is a better motivator than an event to be ready for. (Especially when there's a painting award).

I've been torn between running and Iron Hands Stormlance formation full of Razorbacks or a White Scars biker list spamming grav guns. Both seem like viable lists and both fit into my que of models I need painted for other lists. I'm leaning towards the bikes because they look cooler on the table but I'm still not settled on the final list I'm going to take. The event is in Wixom, MI at Flatlands this Saturday.

White Scars - Grav Spam
Chaplain on Bike
(4) three man units of bikes with (2) Grav Guns per unit
Five Man tact squad in Razorback
Five man tact squad in Rhino

Iron Hands - Stormlance
(3) Tact squads in razorback
(1) Heavy bolter Devastator Squad in Razorback
(1) Landspeeder with assault cannon/multi-melta 

Iron Hands - CAD (not allowed because of restrictions)
Tech Marine on bike with conversion beamer
Grav Centurions in land raider crusader
Three man bike squad with 3 grav guns
Scout Squad in Landspeeder Storm