This might help a little:
http://www.yorkshire-divers.co.uk/fo...ighlight=fa-mi
Tested a Fa&Mi umbilical against my Power 4 led and the difference was quite striking even in the shop, much larger and brighter spread of beam. Until that point I had been quite happy with my little Power 4
However, I like you, would like to see or hear a direct comaprison against something bigger, such as the Salvo 21w9ah!