I own a Sur Ron too, and I don't find the stock battery weight to be an issue. ~30 lbs isn't unreasonable for the average person to lift. It's amazing they packed a dirt bike into 125 lbs. I'm able to lift it over barriers and load/unload it from my sedan, and it doesn't ride far off from a mountain bike. It's only twice the weight of a top of the line e-mountain bike, but has 7x the power output and goes further. Easy decision. It's the most fun machine I've ever owned.
Zero uses 3.6 kwh modular batteries. I'm guessing they are 40-50 lbs or so which is probably around the upper limit the average person would be comfortable lifting and loading regularly. I'm sure they could be engineered to sell them in smaller sized units, but I don't think they're actually hot swappable.
Keeping my eye on this one: https://starkfuture.com/en-us-US/products/stark-varg