There is a rumour that white truffles harvested in Europe by pigs or dogs are much better in terms of flavour than those from North America, hence the reason for the higher price of European white truffles, the main reason given for the aroma difference is that it has something to do with the way the Americans harvest their truffles.  Are European white truffles much more aromatic and flavourful than the North American ones? I would like to try truffles but I do not want to spend too much money on the European ones if the American ones are just as good or nearly as good. 
Goat Cheese is dry compared to many other cheeses.  We make a goat cheese pizza but have to moisten the shredded goat cheese with goat milk into a kind of slurry.  Very low in lactose and tastes good but it doesnt even melt much because it is so dry.  Probably lower in fat too I would guess.  If your espuma is too dry try adding more goat milk to the mixture until it just moves in the blender. 