NC6400 batteries questions

Hello there,

Yes I know, there's multiple threads about this subject already. Sorry to bring it up once more but I just can't find the info I'm looking for and I've been searching the net for days now (btw. many thanks to all the reviewers and helpers/posters in here, brilliant place when one needs to decide on a notebook).

The model I'm thinking of buying (and I can't get another one as only this one's avail. for a promotional price) features:

C2D/T7200/2.0G
Intel 950
14,1" WXGA
1GB RAM
80GB HDD

My first question is about the real battery life of the extended batteries. I've read anything from 1.5 to 6 hours for the NC6400 on it's 6 cell battery, but I guess 3.5 is what can actualy be expected. Now when looking at HP's data ( http://h18000.www1.hp.com/products/quickspecs/12152_na/12152_na.html), those numbers seems slighty too fantastic to me.
If anyone who used the 8 and/or 12 cell battery could tell me how much runtime they realy got out of it, that'd be great.

Next up, I'm wondering about the physical impact of the extended batteries:
Does mounting them make the laptop stand slanting towards the user?
I'm pretty sure that's the case with the thick 12 cell battery, but how about the 8 cell one?
If it does, how much does it additionally lift the laptop?

And finally:
How securely are those extended batteries mounted (esp. the 8 cell one)?

Thank you very much for any answers (and/or links to answers )!