9000 is well known to have polyphony and CPU issues. It isn't always equal if you have a fixed polyphony. My Kurzweil has only 48, but handles denser passages much better than most other's 64. The 9000 had issues with the CPU that made denser passages drop out. It was more a CPU problem than polyphony.

I play pretty layered up on the G70, with denser styles I have NEVER heard a dropout.

Also consider that most TOTL WS's, used by top pros on TV and major tours, have only 128 voices (or less). Somehow, it doesn't stop them from using them and sounding GREAT...