Anyone using a big prime?

[G_Ilott]

Wondered if anyone uses a 300 prime or above (I intend to use convertors sometimes), non stabilised, and whether (a) they have problems with shake and (b) if there are any particular techniques peculiar to motorsport and heavy primes that I need to learn. Panning, of course, is something I became reasonably useful at a few years ago but with a compact 28-200, not a 2 kilo prime.

Thanks awfully.