Gommadin has it's uses. Great for gently sprucing up the occasional spot. A plain old white eraser from the office supply store or 4 dollar 'suede care kit' from the local shoe store works as well.
I've not used the Omninettoyant so I'll not comment on it other than to say I've never been disappointed in a Saphir product. And I would NOT recommend the standard Kiwi spray suede cleaner. It's essentially just dry cleaning fluid and frankly can cause some lesser quality suedes (hush puppies) to bleed dye. And for spot cleaning can leave rings.
This is why I prefer the gommadin method for spot cleaning - no chance of rings from wetness.