I think I'll stick with 2TB... Budget is somewhat flexible as I am looking good performance HDD at a reasonable price. Is WD ultra superior to other models in some way? It's available at 7.8k in FK. If there's any other good models around this price please let me know.
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3TB is a lot of data to loose in case something happens.
Ultra is superior to other models because of two reasons, it's much more compact than other models, thus giving you more portability, and the WD is known for their fantastic ASS, that always counts.
I personally didn't like the build quality of Ultra, it seemed kinda cheap, yes, it was light weight, it actually fit in my right hand very well, but the plastic / poly carbonate around the frame and at the back, well, seemed kinda cheap to me. That's why I sold it and kept the HD-02 (or whatever the model no. is). Because to me it all came down to build quality and aesthetics to me, and the Sony was a clear winner there IMHO.
As I said, you can't go wrong with any brand actually, they all make very nice external hard drives. So you get the Ultra, or something else, doesn't really matter. But yes, when buying a HDD after sales service always matters, thus the recommendation of Ultra.
And ADATA is good brand, quite dependable. The only hard disk brand which I don't like is Seagate, but then again even it might outrun your life.