SSHD may be a possible solution, it's a HDD with a built in SSD cache (you can get software that does this with separate drives).
The most commonly used data is accessed from the SSD cache.
Drawbacks? the SSD cache is not massive, more like 32GB or something, so it's actually better to place frequently used files on separate SSD (the C drive) and move less speed critical things - your downloads, media files etc. to HDD.
A 1TB SSD is for people who only want one drive, or can't be bothered splitting things up - it is a big investment.
I'd say the 500 / 480 is probably the sweet spot for price vs size.
One brand that destroyed their reputation is Kingston, after some bait & switch where later versions of the same model used inferior performance flash memory.
OCZ, on the other hand, under new ownership, challenged kitguru to destruction test 5 ARC series drives - all exceeded their warranty data limit by an impressive amount