I have been changing my buy in for the game I play a lot lately. I have tried really short buy ins and really large buy-ins. I cant really say that one is always better then the other. They do have an effect on your game.
You should figure that on average a hand goes to the river with one raise of a big bet. Many hands don’t go to the river and many more have multiple raises. So you should figure that you should never have less then 5 big bets in front of you. Never be in jeopardy of going all in in limit holdem, it takes your skill advantage away from you.
A short buy in: Usually around the table min or 10x the big bet. I would never recommend this for a NL game. But for a limit game it can be used with some success. First off it may make you play a little tighter when you first get into the game. If you really try not to make your second rebuy then it may make you focus earlier. Also if you lose most of the min then make your rebuy, it will be a chance for you to analyze your game to check for mistakes. Sometimes people lose far to much money when they first sit down because they are excited to play. Some negatives are that it will make you realize that you are losing. If you are a negative thinker or worse, expecting to lose, this will reinforce your thoughts before you have given your solid play a chance to win. That can make you play worse. Small buyins also influence others first impressions of you. Small buy in’s can either mean that you are expecting to win or not lose a lot. People may also think that you are new to the game and have no idea how much you are going to need to play in the game.
Average Buy in: An average buy in is usually 20x the big bet. This is average because its average. People are not really going to think differently about you and it should handle most swings in any game. If you are playing well.
Large Buy In: 30-40x the big bet. A large buy in to a game will make you feel secure in the game and not think about losing all your money for a while. If you are playing good poker and on a cold streak this is a good tool to keep your mind on good poker and away from another losing day. It can make you lose more money then you expect to lose, and allow you to go on tilt far longer then you should with out reevaluating your game. People look at people who over buy as either people expecting to play another game, Someone who is new and does not know how much to start with and someone with lots of money.
There is really a lot more you can talk about on each buy in amount but I figured id just touch on each topic and if there was any interest I would discuss more. If you disagree feel free to voice your opinion.