Done, scrap it in its current form but if the following changes were applied it "could" be a useful tool.
1) Have it run by an independent body (NOT PGMOL)
2) Broadcast live all dialogue between on-field ref and PGMOL
3) Scrap the current "1mm offside" decisions as the current technology simply isn't capable of measuring to this degree of accuracy.
It should be a clear football boot offside. Anything less than that isn’t an advantage. Certainly not a couple of centimetres.