@jpx: Sorry for the late answer. I had a lot of to do last week
You asked for the setups of my TC6.2 and my T4'15. Here they are:
Now some words to the LRP-HPI-Challenge race I worked on the setup for. On saturday before the race, I again compared both chassis against each other. While I love the 6.2 for its steering, in the end I decided to drive the race with the T4'15. My decision was strongly influenced by the very easy handling and the constant fast laptimes I could manage to drive with it. I was able to stay consistent in 10.4s laps for around ten consecutive laps. Something I couldn't do with the 6.2. Therefore the 6.2 had more 10.3s laps in a run, but also more 10.5s laps. So the cars proved to have the same speed. The T4'15 felt a little more easy to drive and a little more precise in steering reactions.
In a 17.5t blinky race one small mistake easily makes the difference between first and sixth place and so it was decided.
The qualifying went well, I was in command the car was ok. I am not sure why, but in the last qualifyer it was twitchy to drive; I didn't change the setup.
The first final was embarrassing for me. I overslept the start signal, confusing everybody behind me. After I finally was awake the pack just ran over my car, leaving me behind laying on the roof. After the marshal put the car back on its tires I had a body tuck and had to visit the next marshal. Shortly after I had the next body tuck. How I would have liked to quit
This time I brought the car to the driver stand and looked for myself what the problem was. I discovered the front body posts were bend (one of the two weaknesses of the Xray-chassis). After this issue was solved I reentered the race with two laps behind. Still seven minutes to go. I pulled myself together with the goal of minimizing the damage. I pulled of a clean run and was lucky that the other guys made mistakes too. So I could get back on the leaders lap and finished second two tenth behind the winner.
The second final was embarrassing too. I made a normal start, but already in the second corner I hit the inside board after the car suddenly oversteered. This time I only lost three places. I won them back throughout the run and was able to pull away. The car was not as good as it was on saturday. I am still asking myself why it became that hard to drive. The shorten this story: The third final went fine. No mistakes from my side.
After this first race experience with the Xray I think it would have been better to drive the race with the 6.2. The laptimes with the T4 got worse over the time and the car was difficult to drive. Of course there are so many sources that could have caused this (I checked the car several time it was technically ok). Maybe the tires were bad or the Xray chassis developes a strange behaviour
Whatever it was, I think the conclusion of my comparison is both chassis are equal fast (in the hands of a clubguy). The T4 has a nicer basic setup and the quality is better. I really like details like the ballbearing anti roll bars. Only two problems: the mentioned weak front body posts and the bad accessibility of the pinion...
The 6.2 should come with a better (more steering) basic setup. Better milling quality (more precise and smoother surfaces for the inner damper) and more accuracy (less slop) in the plastics would be great (I would pay for that). Other than that this car is pretty much well thought.