The book does say that Grade A can be used if the other is not available. I did this with my first Master-Cleanse and had absolutely no problems for 15 days. I lost about 18 pounds too. Maple syrup does provide some minerals, but its main purpose is to provide simple sugars that are readily broken down to provide fuel and energy to the body. The Sugar is not for taste-its for fuel. This slows down and reduces the number of ketones produced by the fasting body and slows down the release of toxins to a more bearable rate. The Master Cleanse is much more gentle and easy than water only fasting and is ideal for people who must work or desire to exercise during their cleanse. My experience has shown very little difference in weight loss between Master-Cleanse and Water Fasting because Master-Cleanse usually keeps the body from going into "starvation mode" and the metabolic rate is not reduced.
You can use Grade A, but B will be more nutritious as far as minerals are concerned.

Whereabouts in New York do you live? The Trader Joes in Larchmont (Westchester) had it a few weeks ago but then somehow it disappeared.

I've done Master-Cleanse with both A and B and sometimes a combination. I did fine on both so I wouldn't worry about it too much.

Good luck!