Yes. Rich simple syrup usually means 2 parts sugar to 1 part water (by volume), whereas simple syrup is assumed to be 1:1. And, yes, some people use 1.5:1 just to confuse things. The sweetness of these syrups isn't as different as you'd think, though. With a little experience, I think you'll be able to look at a recipe and adapt it for your taste. I almost never add simple syrup to a cocktail until I've tasted it (warm, before ice) to get an idea of what it's going to be like. I usually reduce or skip simple syrup, and often adjust the acid by increasing the lime or lemon or substituting dry vermouth for some portion of the sweet vermouth. When making cocktails for others, you need to gauge how they respond to sweet drinks. I consider sugar the enemy of cocktail ingredients. You can always add sugar if you want, but it is hard to get it out of a drink without affecting other aspects of balance. It is trivial to make your own 2:1 syrup. Pour the sugar into a squeeze bottle. Pour in hot water. Shake. Put it down but shake it every time you walk by. Within a few minutes it will all be dissolved. Keeps in the fridge (some sugar will crystallize out) indefinitely. 1:1 will not keep forever.