Paint quality is usually based on several things, including:
1. Covering power.
2. Ease of application.
3. 'Flow' ability ( Flowing to reduce obtrusive brush and roller marks)
4. Durability.
I doubt if F&B or Little Greene actually manufacture the paint from basic materials, ie, oils, pigments, thinners, dryers etc. I could be wrong here but It is quite a scientific process.
If it were me I would use a trade proven product like Dulux, mixed to the colour of your choice in, say, B&Q and name it yourself. In that way you avoid the vagaries of a fancy name which doubles the price. Elephant's Breath indeed ! Give me the old British Standard chart numbering system anyday.