Before our force bought their 902 we looked very carefully at the empty weights / fitted equipment in both the 902 & 135. At that time there was a considerable difference between the equipment fitted to the two aircraft with the 902 having a much higher spec (inc AP) included in the empty weight. It's fair to say that the role equipment fits should weigh much the same whichever aircraft you choose but look carefully at the standard equipment that you will need before role equipment is fitted. Both manufacturers publish a list of standard equipment fitted to their green airframes and of all the options (and weight thereof) that you willneed to add to bring the aircraft up to the spec you want.