This is the text in my Quran which lays the foundation for Ramadan for those seeking more info on its' basis.
Surah 2, verse 185
Ramadan is the (month) In which was sent down The Quran, as a guide to mankind, aslo clear (Signs) for guidance and judgement (between right and wrong). So every one of you who is present (at his home) during that month should spend it in fasting, but if any one is ill, or on a journey, the prescribed period (should be made up) by days later. Allah intends every facility for you;He does not want to put you to difficulties He wants you to complete the perscribed period
and to glorify Him in that He has guided you; and perchance ye shall be grateful.
As far as the night vs day deal, verse 187 goes on to say.................And seek what Allah hath ordained for you, and eat and drink until the white thread of dawn appear to you distinct from its black thread, then complete your fast till the night appears.......
I'm not an expert in Islam but it seems to me both sides have truth in them. Yes the Quran lays out a guideline that says not eating or drinking during the day is sufficient, but at the same time going for longer than that would only show even more disicpline and self-restraint, principles that are cherished in the Quran. It doesn't seem like either one should be condemned, we all have our on path to take and hopefully everyone finds the one that works best for them. In the end if the path taken is a righteous one it would seem that we all arrive at the same destination. peace