I'm still waiting for PSP shipment. So, I'm taking the route for Monster Hunter girl.
There's no difference between PSP and new PS2 version. I heard the only difference with old PS2 version is additional friendly route about Miya.
Tech Gian is the game magazine for people over 18 years old, if you know what I mean. It is the subsidiary of Enterbrain. It jointly develope ADV(visual novel) with Amagami game developers. It is called little extra theater, although the story is quite long. The visual novel is for all age. The disc comes with each monthly issue(February to May).
www.techgian.jp/official/amagami/
About Maya story, she has the high moral and legal standard.
Spoiler:
Remember Junichi(your) failed miserably in Maya route.
In original PS2 version, you ask her to:
1. see you as a man and become your woman
2. marry you
4. teach you subject other than school work.
No matter what you choose, she knocks you out. You becomes unconscious.
The visual novel is the extension of that incident. This time, Junichi did the impossible. After many events, she finally agrees to consider the relationship with Junichi(after his graduation).
Junichi: I hear heartbeats from each other(after embrace)!