I've been using Gookinaid aka ERG aka Hydrolylte aka Vitalyte (its current name) for 40 years. The stuff is simply good. The electrolyte balance and sugar both amount and type are right to optimize water take up, electrolyte take up and not make you sick. (The only times I've thrown it up is when I have the flu or a stomach bug. What does stay down helps a lot and what comes up tastes good.)

The stuff is cheap (~$18 for 40 WBs). I find it better than water to drink when I am riding and after. (I didn't use it for ~10 years when I couldn't find it. Started back up when REI started carrying it 15 years ago and my riding life was instantly better.

All Vitalyte does is hydrate and facilitate absorption. It does not contain significant amounts of carbohydrates, any protein, make promises or perform miracles. I love the stuff.

Edit: Vitalyte is an excellent source for potassium. Sodium is there but not in huge amounts. I make it a point not to eat a lot of salt and the sodium levels in Vitalyte work just fine for me. If you have very salty sweat, you may need to supplement the sodium.

Ben