Well, after many weeks and much scrounging up and down the Hudson Valley region , we were finally able to do a side by side comparison of these four varieties of Pepsi, plus also a comparison of Mexican Coca Cola vs Coca Cola (HFCS version). It took us three days or so to come down from the sugar buzz enought to write this but these are the thoughts...
Of the four Pepsi's: one had HFCS and the other three were made with sugar.
We liked them in the following order: Throwback, Kosher, HCFS and Natural (tied for last). The Throwback and the Kosher were very close. I think the Kosher had a bit more carbonation, but the Throwback had a slightly cleaner and truer cola taste.
The HCFS Pepsi had a pronounced chemical aftertaste that was unpleasant and much more obvious when side by side with the others.
The Pepsi Natural was very strong tasting and too cloying. I thought it tasted like ginseng cola but had none listed as an ingredient, although it did have apple extract and kola nut listed as ingredients. They really need to work on this - too strong, too sweet, and not cola-y enough. I wanted to like this one but could not even finish the couple ounces I poured to taste.
The Coca Cola tasting yielded a similar result - the HFCS version of Coke was not as bitter in a pronounced way but the Mexican Coca cola was smoother and had no bitter aftertaste in any way. Overall the Mexican Coca Cola was the winner of the day.
Of course after all this - I will also say that I do not regularly drink any soda, and when I do, I opt for the diet varieties, so this was all purely a CH experiment in the interest of foodie science. I suppose we should have done it blinded, but that seemed a little but too much of a to-do. But I can maybe make a case for no (or less) bias...as a taster.
[Probably this post belongs on the General Chowhounding Board but I can't figure out how to move it...and I don't want to re-type - LJN]