I am getting a raised mole removed with a radio frequency device. How likely is it to grow back or for the pigment to reappear?

In general a pigmented mole should be removed completely to prevent recurrence and achieve the best cosmetic outcome.  Also it might need to be evaluated to make sure it is not a potential cancer.  Ablation will prevent evaluation since it will be destroyed.  There are  a number of techniques to be considered.  A board certified plastic surgeon can educate you on all your options and choose the best technique  to achieve your goal. 

A mole should never be burned via a laser or RF device. This is incorrect and potentially dangerous. Moles should be sent for analysis. Depending on the kind of mole- Shave or excision are the better techniques. I would see a dermatologist as only dermatologists have training to evaluate moles and interpret its pathology. 

I
feel that it is never appropriate to use any ablative method as your primary treatment
for removing a mole. Regardless of how "benign" a mole may appear, a
biopsy may still reveal it to be atypical. There are many ways to surgically
remove a mole with a minimal scar and have tissue to send for microscopic
examination which is the only way to ensure that it was benign. Ablating a mole will alter its look and make it more difficult to
observe for precancerous changes in the future. Plus, I'm not convinced it will give the best cosmetic result anyway. Depending on their size and location, moles can be safely and easily
removed by one of two methods: a shave excision or an excision with suture
closure. A dermatologic surgeon typically does both procedures expertly and can
decide which would be best for your particular mole.