Hi John,
Go for the 1500, if you already have the skills from the 2000, then this is a nice range of foils to cover all possible winds - I ride the 1500 from 8-25knots, just changing wings, I rarely change the foil, only in super light constant winds taking the 2000HA. 78kg's, same for all my friends here at our local lakes, once you have a bit of a level, you can really drop the front wing size dramatically, my wife is also riding the 1500 after only a short time on the 2000HA to learn.
1750 I recommend to people who want to learn from scratch and will not buy a second front wing later, one for all, but it is often too big once you have the skills/ride in winds over 15knots.