Has anyone tried using Kid goat or lamb milk replacer in the place of using Sumo or the other fat additives, any pros or cons on using it.

Sumo, etc. are higher in fat content by a lot. There is nothing wrong with using those milk replacers, but in general the cost is the same for the major brand supplements that are geared more towards show animals.

Lamb milk replacer is usually 30-35% fat. High Octane Heavy Weight is 70% fat. You need to feed far less Heavy Weight to do the same thing.