Re: only 3/4?
That depends, supply is restricted because many manufacturers were unsure about the value of investing that heavily. If the price starts to drop too dramatically then the cost of investment may not be recovered. Although some have announced new fabs things like xpoint etc are putting a brake on that.
I updated my laptop from an 750 GB SSHD with an 8GB Flash cache to a 500GB SSD earlier this year.
The boot time is directly comparable to the extent that I haven't actually noticed any real difference between them. As far as loading of programs go, the difference is easier to discern the larger the program is but is still not onerous.
When I'm given a laptop to repair, most still have a standard HDD with only RAM cache.
I suspect that the life of HDD could be extended by sticking a small SSD in front thereby giving the perception of being much faster because the boot time is comparable and this is what most people consider.
Once the supply ramps up properly and the cost of a 1TB SSD is less than twice the cost of a 1TB HDD then the consumer market will collapse