Tapentadol (Nucynta) just came out with an ER formulation -- and my cynicism makes me worried that your MD is just looking to cash in on some prescribing incentive.
I've used Ultram ER for 5 years, currently at 300mg and so you have quite a few years and a higher dose still available, assuming you've found some benefit from it.
It has been helpful for me, though lately I think I need something stronger. But that is after 5x your duration of use.
I tried tapentadol IR about a year ago and found it very different in effect from tramadol. The latter offers (or offered) me additional mental focus and energy (given its serotonin release). But the tapentadol made me drowsy and I felt very crummy the day after using it.
Of course we all differ, but it seems to me that if the tramadol has been helping, you might want to decline the switch.
If you do go forward with it, you can cross-taper. That may be the safest. Although the two drugs are supposed to be similar, they have very different effects on me. I have over the years tapered out of the Ultram in order to see what my pain state would be like. I did it by lowering from 300 to 200 in a week, then 200 to 100 in a week, then just to some 50mg IRs for a few days. I was able to do it over a 3 week period without significant side effects, but again, we're all different.
C4-T4 Scoliosis (disk degeneration, stenosis, narrowed neuroforamen, bone spurs), RT hip and SI joint damage from car accident. Also, pectus excavatum, supraventricular tacycardia and mitral valve prolapse syndrome.
Current meds: Ultram ER 300mg daily, breakthrough - hydrocodone 10-15mg, or oxycodone 5-7.5mg. .25-.5mg ativan as needed for sleep, Verapamil 240mg SR (for tachycardia). [/gray