Re Priming Worcester 28i RSF?

No, just as you stated, blead the rads and fire it up, keep on checking the rads for air. But if you're not cutting into the pipework and its just a straight rad swap, all you will need to do is turn off both rad valve(2 per rad) drain the water from the rad, crack the blead nipple to help the water come out, swap the rads, open the valve and top up the pressure, you dont need to drain the system or drop the pressure. Hope this helps

LTGF
September 2008