OK, some small points I'll make here for things that aren't big enough to justify their own update. (I'll probably paste these questions into the LP, so you can consider yourselves co-contributors!)
Is it possible to 50/50 the good and bad ends?
No. There are only three choices available for each guy, which ensures one end will always get more attention than the other. In order to get an ending of any sort you must do all three choices with one of the guys before the end of day 4. Otherwise you're locked into the bad end - not the evil end, but the one where you just fail.
Also I'm kinda curious now, what happens on day 6 if you didn't spend all your time with one person?
All that happens is that
Marin Sango decides there's nowhere she wants to go and just sleeps in for the day. So basically, day 6 just never happens.
In fact even if you spend 6 days ignoring the boys and doing nothing but talk to Ami, you STILL get roped into the cruise on day 7. Tooru's driver pretty much shows up and takes you along while you're on the phone with Ami, which of course means Ami also comes. This time you just get the bad end where Sango fails to collect her entire body, and Sui tells her she has to try again.
So yeah the bad end is pretty uninteresting. The EVIL end, on the other hand...well, I'm about to start work on the Tooru evil end, and I have extremely high hopes.