Yes, the 320 lb Hobie 16 can often be managed solo if you have a shallow launch ramp etc., but not all locations are as convenient.

The 165 lb A-Cat is plenty easy to handle and much more durable than most folks think. 250 lbs would be easy to achieve with modern techniques while keeping costs reasonable, but the original goal of the N15 wasn't a singlehander, rather a durable youth trainer for the Nacra 17 which it does well. This is a reasonable option for mom/dad who want to foil when the kids aren't using the boat.