Possible change to Light Form/GoTE

With the complete overhaul of thieving, and the update that makes the crystal mask basically successful for the length of the spell. I don't believe that there is any benefit in the Light Form/GoTE combination now. I think a decent change would be to change Light Form to increase the Crystal Mask spell duration by 50%. This would allow Crystal mask to work for 7.5 minutes, it would mean GoTE would still be worth purchasing, but wouldn't destroy the sustainability of thieving too much. In my opinion. I welcome thoughts, because right now the Light Form, which requires pretty high requirements is useless for thieving.