Hi Nocturne64
I find it difficult to describe the differences in the sounds/voices/styles quality and i can only comment on the the 805, i purposely didn't look at the 809, simply because it's beyond my means and I can't afford it! I didn't want the 809 results to colour my judgement of the 805
The 605 was first seen on 2012, so the 800 series represents 7 years of technology advancement, particularly in the digital sampling of voices.
I am old enough to remember the difference between FM radio and the old AM radio and i have to say the 600/800 difference is similar.
The new sounds are far more alive and crisper. I was obviously happy with the grand piano on my 605, but the CFX and Bosendorfer sounds are a great advancement, similarly instrumental sounds like the breathy Sax/Clarinet and the haunting Oboe are a revelation.
You really have to hear these sounds for yourself, preferably in a live demo, or via some of the U-tube videos which are now coming on stream. If you are listening via video, make sure you listen via your HI-Fi or quality headphones, rather than crappy laptop speakers. A lot of my playing is on headphones, due to living in a semi!
When you do hear these voices, make sure you are listening to the new voices and not what Yamaha now call the Legacy voices, which are sounds carried over from previous models
The 805 listed as having 1315 voices, i'm not sure how many are new, but I guess several hundred
So, l'm looking forward to delivery and I'll give a further report when i've got used to the new machine.
Merry Xmas to you all.