you can use a stick to check your claims, its really easy, right click and it will show up as gold blocks and glowstone as the borders, from that you mark your own borders.
The claims on the map, caused a few issues and also it looked horribel, the map is much betetr for it, and has actually saved alot of unnneccesary griefing of players land.
We had issues of people scouring the map for specific players lands just to hrass them when they were offline. this has reduced tenfold since people cant do it so easily. Admittedly I for one hated it to start with but now I love that we no longer have claims on the map.