1500 is a joke.
1750 was the best option and it was decent...at one time... But your heavy user STILL had to use 1750x2 or the 1750 in junction with the factory battery or with their 1500. I would say, indeed there was a noticeable different, but nothing too much. It's a smart phone, can't expect much from these batteries at this time. If you're not using the features, what was the point of even getting it, you know?
There is another Verizon released battery 2150 (Btw.. I only go after Verizon batteries, generally unless the batteries are recommended THAT much) is a much bigger difference to that of a 1750. Sure.. there is minimal size being added (I think like a whole .35 In.?) but DEF. worth it.
Now, let's hope the batteries retain their optimal use for a long time and better comes out after time.. 
I did buy the 1750 from Amazon and returned it. I was not impressed with it at all. I purchased the 2150 from VZN and must say I am pleased. Sure the back is a bit thicker, but this battery goes all day and then some. No more remembering to take the charger. The camera lense no longer sticks out which is a plus for me. I was always worried about getting it scratched. The back cover that comes with the battery is a tight fit. The phone feels sturdier in my hands. Occasionally when I need to " hold the phone to my ear with my shoulder" the phone no longer slides. The only downside, can't find a case yet, but hopefully cases will pop up as the demand for them increase. All in all I am satisfied with the battery, because now I can use my phone without worrying about it going dead before I make it home.!!
