Yes the A-cat with external foils is quite stable in a fresh breeze. Small sloop with spin and foils? If you are trying to run a spin at 20 knots across the wind- it will be difficult to manage.
Re versatility:
As previously stated, I put the hydrofoils on this boat in the thumbnail pic for the 38 mile Mug Race last year: little wind= poor result. This year I ran it in the Mug Race with a Hobie18SX spin in light air, and was only beaten by 5 larger, much more expensive cats.