The last update, R2EA023 fixes most of the bugs.

If you want a full qwerty HD phone, I dont think there's any phone that comes close, at this price range (800-1000)

Been using it for 3 weeks plus. No major problems.

i never had any problem with my Vivaz.. never crash/hang..
i think the current firmware is good enough..
my only complaint is.. it needs kinetic scrolling.
kinetic makes scrolling through contact list much easier..

The X6, many ppl complaint of its lagginess. And the carl zeiss, its mostly over-hyped marketing.

Furthermore, the vivaz pro, has a slide out qwerty

Vivaz have higher processor, but in fact cant clock to the highest speed (based on some review), so should be on par with 434mHz.
In term of RAM, yes, Vivaz better, 256 > 128 from x6

camera shooting quality of vivaz is more than enough, and what's more, it is the cheapest phone with hd video recording..

u can check the examples of its cam shoot here

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Added on January 11, 2011, 6:05 pm

The picture quality on the Vivaz Pro is better than the Carl Zeis on the X6.

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Added on January 11, 2011, 6:06 pm

Should be the same. Download the Equalizer app to enhance the sound quality
Again, it should be the same. The only major difference is the qwerty keypad and 5mp cam on the Vivaz Pro
Yes, it is scratch resistant, but always put on a screen protector as a precaution
I'm currently using a set of Creative EP-630, very balanced 

Hope that helps.

RM50 from here. OEM, but when I compared with original set, its the same

OEM = Original Equipment Manufacturer
Read here

I've installed Ferrari GT Evolution (64MB  ), Rally Master Pro (17MB. Had to install it manually since surprisingly mine did not come with it) and Need For Speed Shift (81MB  ). So far I cannot run the NFS. I think something went wrong during installation or perhaps not enough memory. 

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Added on January 21, 2011, 10:55 am

This is why I say the method you mentioned earlier is very mafan. Imagine having to send 17MB mail for them to sign it for you and then download it to install... 

Using SISContents in this case is much better and faster.

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Added on January 21, 2011, 10:56 am

I also transitioned from K810 and I'm also a little lost with Symbian when I got this phone. 

For those who have not signed, I signed mine at the following link;

http://www.s60certkey.com

You need to do a simple registration at the site and wait 24 hours or so for them to reply with the relevant files.