I own both and really like both equally well. I really want to sell the dex408 as I have 2 811(e)'s and the nitro buggy and truggy but damn the thing just drives and jumps so well. The dex408 drives awesome and jumps very well and you would not go wrong with it, not to mention parts are a lot cheaper than the Serpent.

With that being said the 811(E) quality wise is top notch and the shocks are great. Serpent is always on top of their cars with constant upgrades and the buggy drives and jumps really well. It is harder to work than the Dex408 put I really like the layout. There are a ton of tuning options for the 811(E) a lot more than for the dex408.

If you can get someone to let you drive one I highly recommend it because that might be the only way you will be able to decide.

I will say that I love my nitro 811 and don't care for the nitro DNX408.

I hope this helps.