I debated the 500wh vs 700wh vs 2x 500wh batteries for a long time and in the end I bought a 2020 Kenevo comp and I’m starting with a single 500wh to see how I get on.
I can tell you now that you could ride on a flat road in eco mode with a tail wind while slipstreaming someone and you'll be lucky get 70+ miles at 95-100kg from a 700Wh contrary to what the range calculator may lead you to believe.
The range calculator says a rider weighing 100kg riding on a flat in eco should get...76 miles on the 500wh and 106 miles on the 700wh. I then changed only the terrain from flat to hills and the numbers are 39 miles for the 500wh and 55 miles on the 700wh.
I am floating around the 95-100kg mark myself and using a 500Wh the best I’ve managed on a a very flat trial ride in relatively dryish conditions was 22 miles with just over 50% battery left.
So based on the above I’ve done some very loose estimating based on 22 miles using about 50% of my 500wh battery:
250wh = 22 miles
500wh = 44 miles
750wh = 66 miles
However a 750wh doesn’t exist it’s 700wh and my estimations don’t factor in the additional weight.
I am now almost certainly going for 2x 500Wh batteries as not only a viable option to a 70+ mile ride but also as a cheaper option as the 700wh battiers are £1100 but you can get 500Wh for £500 at a few dealers.
I hope this came across as informative and not a rant because I bloody love my ebike

and I know this is based on my Kenevo rather than a Levo but it’s real world.