How many handed at a table?

There are evenings when we end up with a number of players where we are either crowded at a single table or short-handed at two tables. It is convenient when we either have clearly enough for two tables or clearly not enough for two tables. Take for instance tomorrow. We have nine commits. Jason said MB is "likely," Mike "may come," and Chuck said he is 50/50 which leaves us with anywhere between 9 and 12 players. Further complicating the issue is the recent trend of two players playing Magic. So I would like to bounce the following rules of thumb off of you (exceptions could always come up of course).

* In general, with 0-9 players everyone plays at the large table, with 10-17 players half play at the large table, half at a round table. Large table gets the extra player if there is an odd amount.
* A pair of Magic players welcome to leave the table when we are 9-11 handed and we will stay at one table as long as it seems likely that there will be enough interest in keeping two players out playing Magic.
* Magic play discouraged if we are 8 handed or less so that we can keep a full table of poker.
* If we have at least 12 people say that they are in for poker then we will start at two tables. Anything short of that we will start at one table and break out a second table when we reach 10 players present.
* We will keep both tables balanced to no more than one player difference with the extra player being at the larger table in event of an odd amount.
* If a player needs to be moved, the player and the new seat will be determined by random draw.
* If we are at two tables and enough players leave to bring us to 9 players we will condense down to one table.

Do those guidelines sound OK? I don't think they differ much if any from what we have been doing but I wanted to see if that was working for everyone.