rdc85 :
btw u need to care when buy hdd do a testing after setup lately newer model hdd is more prone to failing i got some drive that fails before a year,
contrast with my 7 & 5 old year old hdd that still running fine.......
That. Thats why I'm not using Seagate drives anymore since in few last years 3/3 of their drives was sent for RMA.
I might be wrong or unlucky but when you burn once you are somehow more careful in the future.
And thats exactly my point while having 1 drive only is a bad choice nowadays.
Yes you are correct to not use low rpm drives in general as a single drive, its bad in so many ways.
But when you consider they are cheap, its perfect as a backup/storage device... who burns cd/dvd/br nowadays when its actually more suitable/faster/economical to simply buy a huge cheap drive, put crap on it and even detach it and put it to a rat hole. Its funny but true.
You must remember another thing, copying files from a slow as crap HDD to another drive will in vastly most cases be faster than copying files within the same but fast drive, since in first scenario both drives are doing a single job (1st reads, 2nd writes) in a single setup one drive do both thats why its theoretical read/write speed is almost a half.
I'm not gonna put more arguments about perfect everyday usage solution because there is no such, but to finally answer the topic question:
1) 1TB is enough for a gaming rig?
Of course it is... an OS needs how much 10-30 GB and an average game needs mostly 5-20... count yourself.
2) Is it good to have 2TB drive?
Ofc it is, bigger is better (for some)
3) Is it economical, safe or optimal setup?
Read all the posts above... its far from being a YES on all those questions.