I don't think that IH's got some practical use in game, at least not at higher lvls. Only if you want to practise your magic level :)
UH's are very important at team hunts at high lvl grounds, as guy before said he can heal between 1200-1800 health. Many time it can save the life of blocker (paladin or knight) when he got trapped with many monsters, or when healer take longer time to come. There is many different situation when you can use it to save someone life.