F1's are ACE!!!
I ran at Tamworth with a 10.5 and 2s lipo, it was fine.
Don Valley is a completely different ball game. Not raced F1 there, but the surface is like a rubber running surface, hence the 'no addative' rule, and it is very dusty and cold so grip takes a while to come up...even with a touring car. So with an F1 weighing only 1.1kg, it will be difficult to get any grip.
But carpet and outdoors, they are fantastic.
Well worth £75!!!!!!