formed with Vm + （難い) にくい, making it an i adjective.
The different is that 難い is added to a verb stem to change it to an adjective, whereas 難しい is an existing adjective meaning 'difficult', and thus can't be conjugated to a verb stem. For example: That word is difficult to remember (lit. That word's remembering is difficult.) その言葉が思い出し難いな。 as compared to: Remembering that word is difficult (lit. That word's remembering is difficult). その言葉は思い出すことが難しいだ。 EDIT 10/15/07: You're right; thanks tiger!
Hey groove in your second example. I don`t think you need the する. 思い出す is a verb already. other than that I like your explaination very clear I added a vocabulary note for yasui
What's the difference between むずかしい and にくい?
As for the comment in Notes, t should be にくい, not いくい. typo? In kanji 'にくい' is in 難い or 悪い 'verb conjugation + にくい'.