With 3 guys, any one of them could want to move in with a girlfriend, have a dispute with each other, grow tired of each other, move into a 'trendier' place etc. From the stories I'm told, a lot of younger people tend to get sick of each other in these situations.
I tend to agree. From my previous experience renting with 2 other people, there tends to be too many variables and conflicts of interest. I rented with 2other guys at my first year at Uni. They already knew each other because they were studying the same degree. They were ok blokes, but while I wanted to study, they were at the uni bar coming home at 3 or 4 am on a regular basis. Then there was the issue of who's turn to clean, cook etc. I finally got sick of it and moved out. My theory is always go for an even number of tenants, ie, two people will generally get on better than three. If there are four people and it turns to custard, there will usually be two that will remain to continue the lease. Just my thoughts and experience.
Phil.