Hi tribbles,

Yep, all that would work - I was just demonstrating that what was required could be done simply.

In the past I've used PWM to modify the VRef voltage - however I've always spotted some ripple with a single stage of RC filtering (I think my PWM was at about 5khz) so always added another. Don't think it matters that much as long as the voltage is approximately right though.
Usually I didn't bother with the VR, having options in the PIC to set the current (either with links setting the most common values, or via a menu on whatever display device I'm using).

Monitoring the VRef voltage I've never found to be necessary - although my initial attempt did exactly that. I have in the past though (when building buck/boost converters to drive LED's) made self starting regulators using the PWM on the PIC and used the analogue inputs to monitor the voltage and adjust the PWM. That's a very interesting experiment in feedback loops... )