I've always used the data folder myself without problems aside from when it was disabled. After they disabled it I wasn't able to get the mods to work via data.ini unless I edited the adata/sdata .grf's themselves. :/ Took me months to figure that one out. I find it easier to just plop them in and out of data, change loading screens, edit scream/frost joke and just change maps/teleport rather than having to compile a .grf. The old mods that GMs posted on the forums such as the valk helm and christmas? maps use the data folder, I'm not sure about anything they may currently post.