In my and others experience, the best withdrawal method is a process of cutting back your dosage over time. Going into a rehab unit is pure hell. And anyway you are not an addict. Take it slow friend. In my humble opinion the vicodin you may want to stay on the longest. Percs make me feel depressed. Vicodin does not do that. I am a pain patient. This may sound counter intuitive but oxycontin acts longer with getting a less addictive buzz or high like one does on vikes(hydrocodone). The war on pain patients is a cruel broad brush that punishes people in pain along with addicts. Addicts do "kitchen chemistry" with oxycontin to get a fast release that is very addictive. When used correctly oxycontin is a good, safe and probably imho less addictive than vicodin. but people in pain should also be allowed to take short acting vicodin. We that are in chronic pain should not be punished with these draconian new pharmaceutical laws just because there are others that abuse them. they are lumping pain patients in the same lot as addicts. the war on anything is a sleazy market for the police/prison/banker launderers complex who rule our politicians, lawmakers. It has got so bad that pain doctors are afraid to keep rx ing pain meds
Every doctor is different, some are 'more aggressive' when it comes to weaning off of narcotics, while others take it slow and steady. In fact, some states have "published guidelines" for withdrawing off of opiates (e.g. the state of Utah publishes, "A decrease by 10% of the original dose per week is usually well tolerated with minimal physiological adverse effects").
600 to 700 pills sounds like you have been on pain medication for probably around 6 months or so, which means your body's chemistry has changed enough that a good, thorough discussion with your doctor would be in order.
I would trust whatever your doctor says -- if he's qualified to prescribe the heavy-duty opiates your taking, it is likely he has a good deal of experience withdrawing patients off of those meds. Don't hesitate to give him feedback, though! Communication is key.