I think it would be nice to add a toggle switch to bypass the PWM and revert the mod. This way you can have maximum lux, or a dimmer adjustable setting as desired.
It's been a long time since I saw this video, so I don't remember how it worked out for Dave, but I've used the exact same circuit before and IIRC, at the maximum end of the pot range, the duty cycle becomes too high for either the 555 or the switching transistor (I used a fairly large MOSFET with a high gate charge, though, and couldn't be bothered to figure out the "problem" - I called it a feature), and the load just turns fully on anyway.
Of course, if your pot is too scratchy, you might have trouble slamming it hard up against the end stop for full resistance. I recommend newer ones.