Twin tee oscillator

A twin-tee audio oscillator is a very useful item to have around the shack. Looking around the net for suitable circuit values yesterday I came across this page by G0XAN http://homepage.ntlworld.com/g0xan/twin-t.htm

I shall be using one this week with my CW keyer to send slow CW (QRSS) on 1.2kHz and 8.97kHz. For very slow CW I'll need a much more stable oscillator probably a crystal and digital divider, although many on the "Dreamers Band" are using a DDS source.