i have a short video i'm trying to get uploaded...
in the mean time, here are some pictures of my gt-r on my mini-96.
here is some of the tile transitions in reference to the dnano scale. yes, they exist and on some tiles, larger than others. none of these caused the car any trouble.
here is the car at a 4 corners transition. nearly perfectly flat seems.
the rial height is a bit overkill for the dnano in height but your not going to get a car jumping the rails, thats for sure.
at the starting line, you get a real sense of scale for the texture
i found any bumps to be mild at worst. nothing that would cause any concern at all. what the dnano does not handle well are curved surfaces. my track has bumps, banked turn, etc. and these made steering a bit tricky as it seemed to max out the suspension travel at times making the car a bit unpredictable at these locations. the 30cm tiles do not bank/curve as cleanly as the 50cm tiles due to the smaller size. the tension force between the tiles is greater than some of the connections can withstand. it's far less than the 50 cm tiles for sure. what you can do to ease the pulling force on the tiles is to underlay cardboard over any bumps/banks. it seems to spread the curvature out a bit more creating less tension on the tile connections.
one thing i've done before was duct tape the tiles together on an old 50cm offroad track course. this allowed me to bump/bank the tiles as much as i wanted. it's a bit extreme but it didn't bother me on the old 50cm offroad tiles. i'm not sure i would do it on a track i planned to reconfigure though.