I was really excited when I read your post about this, since I too have been looking for something to invest my money in. When I started looking more closely at the stock performance since it went public in Jan 1990, I was somewhat disappointed. The stock did perform exceptionally well until mid-1998, at an average annual return over that period of about 31%! And while that's great even for the dot-com growth period, we do have to keep in mind that it was, after all, the dot-com growth period, and almost all stocks were doing great then. The stock then lost about 40% of its value over a period of almost 2 years, and since then (early 2000) until now it has had an average annual growth rate of about 15%. Over the whole history of the stock being public, it has averaged about 17% annually.
My point of all this is that I think it's unrealistic to think the stock will perform at 23%, and certainly not on a consistent basis. The natural of all stocks is to be volitile, and if you look at the history of the stock, while it certainly has risen over time, it's had down periods as well. I think it's fair to differentiate the private period from the public period. If it has grown at an average of 23% since he took it over, and at 17% since it went public, it grew at more than that from the time he took it over till it went public.
Ty, considering the stock's performance since it's gone public, you might want to reconsider your strategy of always owning one share on margin. If you take 10% out of the numbers I quoted above, that's a big chunk.
Another thing to consider, is that hasn't Buffet pledged almost all of his fortune to Bill Gates' charity? I'm assuming Buffet owns a serious percentage of the total of Berkshire Hathaway. I'm not sure what happens after the money is gifted to the charity -- whether it holds it as stock or sells it off, but that could also add some uncertainty to the equation, if a decent amount of Berkshire's stock is going to be sold off over the next few years.
I'm concerned about Buffet's age as well, and am not quite as optimistic as Ty is.
Anyway, I would recommend for everyone to check out the stock using Yahoo's great new stock tool! The best part is you can drag it graphically (on the bottom right, where it says "time range") to see the performance at various points in time:
Its ticker symbols are BRK-A and BRK-B