Also, just wanted to mention something about the aluminum chassis plate.
A lot of people worry that the aluminum will bend too easily or become permanently tweaked after a few board taps......
Last weekend I had some pretty nasty hits (17.5). Our layout had a full-throttle right-turn on the left side of the track that had a fairly square apex. We don't have ClikTrak at the moment. I hit this apex at full throttle a few times, along with a couple of tumbles through the sweeper. Over the two days I ran over 30 or 40 battery packs through the car.
I did NOT even need to de-tweak the car once. There was not one time on the track that I felt something was off or that a part of the car was out of alignment. On the first pack I set the radio trim for exact turn angle left and right, and so that the car went perfectly straight on the backstretch. 40-something packs later including all the above mentioned hits and through qualifying/traffic the car would still track so perfectly straight on the backstretch that I did not even need to have my hand on the steering wheel.
Basically what I'm saying is, that if you have a hit hard enough to permanently tweak or bend the aluminum chassis, you probably would have broken a CF plate or done enough damage to other parts that it would cost the same to repair either way.
Unless you run on a huge track or the boards are made of pillows, I would always run an upper deck at the least for structural support.
Hope this helps with some of the confidence issues people have
