Seems to me that only you can make this decision, based on your love or lack of love for the SDX1000. If you love it very much, just try to get the re-tip as close as possible to the original, i.e., match the cantilever construction and the stylus shape to those of the original. Personally, I always thought the SD900 was way over-rated, but I have never heard an SDX1000, and my opinion has nothing to do with this decision. Also, contrary to what you wrote above, Sound Smith probably CAN do the re-tip for less than $600, maybe way less, depending upon your choice of cantilever and stylus shape. Only issue with SS is that they may not be able to supply exact replacements for the cantilever/stylus. On the other hand, their sapphire cantilever/OCL stylus shape sounds wonderful on my Grace Ruby.