I would like to point out one of the finer points of fantasy football. Of course you know about balance in terms of not loading up on a single position. But I suggest there is a finer balance than this, and it comes in the form of player compensation (and not the monetary type but one player on a team picking up the slack for another player). If this seems esoteric for now, let me try to clarify using myself as an example.
Last year the Vikings were a good team, there's no doubt about that. Adrian Peterson had a career year and so did Brett Favre, Sidney Rice, and Visanthe Shiancoe. There were plenty of points to go around. Because of this, and the fact that I had Peterson, it benefited me greatly that I had Rice as well. The thinking is this, although I limit myself in the ability to put up ridiculous numbers with my top WR and RB on the same team, I also make my team more consistent. It would have been better for me to have Favre and Peterson instead of Rice and Peterson simply because I could really get points from basically every bit of offense and not just the receptions by Rice and the rushes by Peterson. I also did the same thing with Derrick Mason and Ray Rice. The idea: find a high-powered offense and get two players on it (one in the passing game and one in the running game).
Contrast this to Everett's team. This was also a great team last year, but there were NO players on his roster playing for the same team. This led to some ridiculous weeks (week 2 for example with 224 points), but also wild swings from one week to the next (week 1 he only scored 72 points).
On the other hand, it is a bad thing to roster more than one RB or WR on the same team other than handcuffs. If the passing game or running game is shut down, both players suffer. Moreover, it can be maddening trying to figure out which RB to start (ask Ben or Tyler).
Finally, it is not necessary to roster players from the same team if you can find a favorable matchup schedule which serves the same purpose. This, however, is much more difficult than getting two players on the same team.
Just DO NOT draft more than two players on the same team if you plan on starting all of them. This can be a disaster. Just see my '08 draft (i.e. worst draft in history) for evidence of this plan backfiring.