Hi, Clem-
To be clear, "3drefit -deobllique .." will purge obliquity information from a dset: the input dset is overwritten, and the obliquity information is removed---it will appear in the same place in the GUI, too. The data is not resampled/regridded, so it is not blurred at all.
"3dWarp -deoblique .." will *apply* the obliquity information, so the new output data will *not* have obliquity, but it will appear in a different spot in the GUI---it should be in the spot where the obliquity information had placed it. In this case, the data is resampled/regridded, though, so it will get a bit blurred.
--pt