The nice thing I thought about Sharira Gaon is that to him Rava and R. Yose [Bava Batra 22] come out parallel. Even though to the Rishonim, there are ways of explaining things, still the approach of Rav Sharira Gaon makes a great deal of sense, For to Rava one can not dig a hole right next to the border of his neighbor. And to Sharira Gaon R Yose agrees with the sages that it is incumbent one one who might cause damage to move away some distance between himself and his neighbor. Otherwise it is hard to understand how R. Yose who holds it is upon the one that might be damaged to distance himself and Rava could agree. [Sharira Gaon says R. Yose agrees with the decision of the sages, but not their reasoning- but also that the law is like Rava only in the case of a pit where just by digging he causes the ground on the other side of the border to be weakened. Thus to Rav Sharira Gaon, the the law is to bring close to the border anything besides a pit is ok-- as long as there is nothing there at the time that can be damaged.
The Rishonim explain this differently (1) Rava is saying his law only in the case of a pit [hole in the ground because that is directly damaging the field of his neighbor; i.e. "his arrows". (2) The Rif and Tosphot say who comes first to the border can stay, and the neighbor who wants to put something on his side of the border can do so if he does not mind. But the first one can stay. (3) Rambam says the first neighbor can put something there, but then if the neighbor puts something that can be damaged next to the border, then the first one then has to move away.] (4) Some say the only permission is if the neighbor is new and bought that property after there is already something at the border that can damage.
The Reasoning of Sharira Gaon is that one statement of the Gemara is that R. Yose is saying his law in answer to the sages in one case but really he disagrees with them in all cases. The another statement is that he agrees with them. So Sharira is deciding with the later statement.
