Sospan, Snow foam advantage is it's designed to hang on and lift dirt thus removing some of the chances of micro scratching. And from experience it does seem to work. Selective buying and I find it works out cheaper than shampoo by a long way.
For shampoo I buy the supagard shampoo sachet's, one in a large bucket with a grit guard in the bottom. This stuff is super slippery and with a micro fibre cloth works so well, Best I have ever found!
One final tip when cleaning the MOG is to cover the engine with heavy grade polythene, visqueen type heavy 500 grade. especially where the 4 cylinder engines are concerned! Plug well's in the head fill with water otherwise and is hard to remove! It's those bonnet louvers you know!
Not trying to teach egg sucking here Sospan, rather for the benefit of those new to the world of MOG ownership if they read this!