Is "instant flour" worth bothering with?
Instant flour has the advantage of speed and ease.  You can pretty much always do without - but for home cooks in a hurry, it can be an easy solution.  Its used for sauces, but sometimes recommended for pastry work because of the ultra low protein content.

Normally, when adding flour to a sauce you'll need to make it into a slurry or roux and mix in correctly to avoid lumps.  Then you'll need to cook it for a bit to get rid of the 'flour taste'.  

With instant flour, its just pour and stir - no clumps, no waiting.  My understanding is that this is ultra low protein flour that as been flash hydrated, cooked (possibly with steam), dehydrated, and then finely ground.  This means its pretty much 'ready' to use - it won't taste 'floury' since its already been cooked and the superfine particles are supposed to not clump.  (It may also contain some malted barley flour as a dough conditioner). 

You could try (this is just an idea) making it at home by basically repeating the above process - steam cake flour, dehydrate, grind...but I don't know why you would.  If you going to do all that, just make a slurry or roux or use cake flour.



This site lays out a few interesting uses.  Using it for crepes because it will hydrate quicker.  Using it for pastry work when you can get pastry flour and you don't want the bleachness of cake flour.