I'd also like to hear an answer to this. I'm confused about what a good customization is in regards to SSD/HDD, price & performance-wise.
I'm also considering the NP9170. Even wondering if I should go all SSD no HDD.
If your computing needs are satisfied by a 128gb SSd then you can however some factors to keep in mind:
1) You cannot do not & should not defragment or format an SSD
2) Repeated flashing like downloading movies and stuff and then erasing them, if you are into this you would need a seperate SATA disk for it as repeated flashing of SSD when it is the boot drive makes it unstable and decreses the life of the SSD