Hi Mike, really appreciate your efforts in regard to adding Canto support. Can't wait for Canto audio.
Just adding to dom's point above regarding lazy pronunciations - yeah gotta be careful with that, especially when recording professionally for a dictionary - e.g. 五 (ng) pronounced lazily as mmmm.
Might wanna take a look at this for a brief overview:
http://www.cantophilia.com/2007/11/lazy-pronuncations.html
As for Canto pronunciations, I agree HK would be the way to go - considering Hongkongers would consider many mainland (even Guangdong area) and diaspora pronunciations to be inaccurate/off - 歪音.
Also, I hope you guys can get Longman's HK traditional C-E dictionary! (So I can throw out my book version!)