i went with the hellfire because its easy to get parts from hpi and their cust serv is the best. i cant even tell you how many free parts they have sent even when its my fault. parts for my savage 4.6 that is. i havent yet broke my hellfire yet and ive got a .5 gallon through it so far, except the steering servo, it was junk.but, hpi said they will replace no problem for free.
but i was in the same situation on deciding and i went for hellfire.
hpi has proven to make a very durable savage so i figured they would extend their durability to the hellfire.
i also looked at the thunder tiger but parts were to hard to come by and i called their cust serv before i bought to ask a few questions about the truck and they couldnt tell me anything about it.
the only draw back i see on the hellfire is the weight of the truck. from what i understand the jammin is like 2lbs lighter?
anyway the hellfire is a very fun fast truck and this summer i hope to race it.
if you want to do your own engine and all i would definatley get the jammin.
i love my hpi nitro stars .