I had the 8ight 1.0 when I got the RC8. I took both to the track with pretty much equal equipment and used the same tires on both cars and ran qualifiers with each back to back. I ran my fastest lap with the Losi and the fastest qualifier with the RC8. Keep in mind I had dailed the Losi in already and was using the stock set-up on the RC8. At the end of the day I couldnt say which was really better than the other but knew I had to let one go because switching back and forth was not feasible.
I offered both for sale and took the first deal that came along. The 8ight was sold and I kept the RC8.
Since then I have made many improvements to the RC8 both in set-up and with hop-ups like big bores that werent available when I originally tested back to back. I have done extremely well with the RC8 and when I drove a friends 2.0 when they were released I still prefered the feel of my RC8 although admittedly the 2.0 was still good.
I feel the biggest difference between the cars IMO is the way you have to drive the Losi. I felt like I could really push the RC8 much harder. I could run good laps with both but if I got trigger happy with the 2.0 I would overshoot jumps and the back end would get loose.
I'm not going to say one is better than the other. Nobody can know for sure which is best for you. If you dont like your RC8 then maybe switching will be good but if you do like the RC8 I would stick with it at least until you can try the new parts on it. You wouldnt be able to get much for it right now if you were to sell it but with the new parts installed if you wanted to sell the resale would be much better.
I think about this a lot myself and there is one thing that really bugs me about the Losi and that is the carb angle. On the 8ight I had and even the 808 I had problems with the carbs sticking. I'll admit it has to be partially user error on my part but I tried every trick I could think of and still had problems.