@ Herve and Jake Lo
Thanks so much for the link and heads up this is reassuring I'll move this to D630 but here for now since I believe it would help someone
I have the sound working with a stable Yosemite using voodoohda.pkg 2.8.7 by installing it and editing the chameleon boot.plist string to enable it. I then enabled permission and now have a stable Yosemite that's boots normally without -f boot flag.
Using the bootpack from Herve please remember to add the kext which chameleon may not see as mentioned by Herve in the link above.
I have managed this using the bootpack from the link as well on three testbeds. T9300, T7500, T7300 NVidia Quadro nvs 135m using chameleon bootloader 2.3 svn r2401, r2468 and the most current r2700. Also for the kernel trying both my Yosemite extract and vanilla from Herve.