Thevoiceofreason,
have you ever personally measured the value of g at two different altitudes? Have you ever noticed that there are allegedly different values of g at identical elevations in different parts of the world? There are some major inconsistencies with what RE'ers have said about this.
Straw man. And if any RE'er said g depends only on altitude, they are wrong. Latitude, local geography (like giant mountains nearby), and earth's distribution of mass also matter. So we actually EXPECT "major inconsistencies" if we were to assume naively, and as you seem to have implied, that it depends only on elevation. No one says this, though, and this is not at all what RET claims.
But the bottom line is that it does not matter. If there is any statistically significant difference between the value of g in any two places on the earth, and yet these two places aren't accelerating away from each other in terms of how high they are, then the earth cannot be flat.