I made a cap-tuned one as well, also using a dual 365pF cap. Nice thing about the cap is that with equipment that use one (e.g., the Hewlett-Packard 200CD audio oscillator), you can bend plates to make the frequency readout dial deadly accurate. No amount of resistive tweeks can properly change a pot's tracking within its stops. I did that back in 1972 with a 200CD that was off a bit. My results would have impressed anyone in Palo Alto.
But I wonder if the double-helix resistive winding of a -- well, let's use a tradename to aptly describe it -- a Helipot would cause the oscillator to have upper frequency limitations.