I think multi-tabling is a double edged sword. It relieves the boredom of a slow tourney (a subject for a new thread) and to a point, allows the player to play more tables which equals more experience which can equal an increase in the BR.
However, it's come to a point where "extreme" multi-tabling is affecting the way some players play the game. Playing 18-20 or more tables and up to 90 (or so I was told in an E-Mail from PokerStars
Tech Support) essentially removes the skills many of us take pride in when playing the game either live or on-line, and the player becomes more of a robot utilizing numerous pieces of software to assist them in playing that many tables.
Out of interest, how many tables do "YOU" think you can play effectively while utilizing your learned poker skills, and without the added use of some software.
For me, 3 in a HP game, and 4 in Turbo tourneys. I don't normally play any slower than that unless it's a big $$ tourney when I only play 1 to concentrate on the game at hand.