the reason the megs scratch-x is better is because the compound granules disintegrate the harder you work the polish... this means that you never just continue to scratch the surface as you work it... it does its job so it is very safe
in answer to the OP's question.. the best scratch remover I know is Dubplate Dan 
you called???
im personally not sold on the megs scratch-x im pretty sure its just got fillers in it
ive done the rub between the fingers test and it feels like theres now abbrassive granules in it, also tryed it by machine aswell as by hand and its not upto the job im afraid but thats just my opinion.
