We all identify with a horn that we've grown up with and know all the "ins & outs" of what to expect when we breathe through it. It's a truly symbiotic relationship.
It reminds me of Kenny Douse, who was the saxophone soloist with the U.S. Marine Band many years ago. As was expected of wind players in the Marine Band, he was also a string player, a violinist, and was proficient enough that he later became a member of the National Symphony Orchestra. Whenever there was occasion for a saxophonist, Kenny was the first choice ---- and he was terrific ! It was the practice in those days when an instrumentalist retired from the Marine Band that they were able to take their instrument with them when they left. Surprisingly, when Kenny retired, he indicated his choice to take his favorite instrument with him in retirement, but was refused ! He was told that his instrument was far too valuable [a Stradivarius among Selmers !]and that the Marine Band would retain it to pass along to whomever became the next saxophone soloist in the ensemble. Of course, he accepted their decision. When the replacement saxophonist was presented with the "Stradivarius among Selmers" he played a few notes, commented on the "leaky, unplayable carcass" with which he'd been given to begin his career with the Marine Band, and flatly refused to use it !
My entire point is that your relationship with your King 3B is unique and only you can decide whether to replace its place in your life. It's a lot like the relationship with a spouse ---- special !
I have a King Duo Gravis SS that is as special as your 3B. IT knows ME better than I know myself ! Good luck in your decision !
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Cheers !! Bob