At the very least, the dictionary obliviation attack is pretty clever. In retrospect, it's kind of obvious - but no one else in canon or MoR does it. (Harry could think of it easily based on his experiences with his occlumancy instructor, but hasn't yet, probably because it's a very Dark technique or because he can't yet obliviate.)
It is clever, although if he has to make enough attempts in a row, Hermione may notice the missing chunk of time. That wouldn't be enough info in itself to reveal what's been going on, but it should make her suspect something malicious, and possibly even that she's had her memories tampered with.
Update: Discussion has moved on to a new thread.
The hiatus is over with today's publication of chapter 73, and the previous thread is approaching the 500-comment threshold, so let's start a new Harry Potter and the Methods of Rationality discussion thread. This is the place to discuss Eliezer Yudkowsky's Harry Potter fanfic and anything related to it.
The first 5 discussion threads are on the main page under the harry_potter tag. Threads 6 and on (including this one) are in the discussion section using its separate tag system. Also: one, two, three, four, five, six, seven. The fanfiction.net author page is the central location for information about updates and links to HPMOR-related goodies, and AdeleneDawner has kept an archive of Author's Notes.
As a reminder, it's often useful to start your comment by indicating which chapter you are commenting on.
Spoiler Warning: this thread is full of spoilers. With few exceptions, spoilers for MOR and canon are fair game to post, without warning or rot13. More specifically: