erm.... hmmmm.

maybe?!

i suppose it depends entirely on what you're making/using it in. i can see it working pretty well if you're normally using the egg replacer in pastry, or to firm up and bind other savoury things like beanburger mix. i often use instant mash to thicken stuff up when making patties, and know that potato scones/potato bread/potato pastry can be made sucessfully with instant mash in place of real potatoes, so it makes sense that it might work.

i can also see it not working so well in sweet things like cakes, especially if you accidently ended up with cranberry-cinnamon-orange and buttery garlic and herb instant mashed potato flavoured muffins- i'm sure you'd not do that, but its something i can see me accidently creating. 

can you get potato starch cheaper by the scoopful at a bulk bin type store- then use it in place of nrg? thats where i get mine- those little boxes of egg replacer in the grocery store (like many little boxes of things in a grocery store) are a total rip-off. or what using about corn, tapioca or arrowroot starch instead of potato starch? i expect the prices are gonna be about the same for the various starches, but i'd reckon they'd all probably be less than boxes of nrg. hmmm.

did you know that in many recipes, you can completely omit the egg replacer? i don't even bother with buying or using it anymore, i generally just skip it in the recipe nowadays, and i've never had a problem- though obviously you would struggle if it was the main ingredient to a recipe.

you can also use various other agents to replace the various properties (binding, raising, emulisfying etc) of egg replacer- like applesauce, veginaise, mashed banana, pureed silken tofu, canned pumpkin, flaxseeds ground or blended and mixed in some water to make a gloop, a little extra baking powder, or a mix of baking powder and oil and water stirred slightly in a cup, etc etc etc. just don't ask me which one to use when or how or for ratios.

yeah... i bet i was really unhelpful. i dare you to just try it, and see what happens.  then report back. ;D