I cannot attest to accuracy of one product line over the other,, I did not acqire my LB 2.5 USB until after I had killed my govt surplus power meter. But, one thing I can faithfully state is that, given consistent setup, fresh bat.s or bench supply, sinking, distance, ambient temp, ect., My USB has always been consistent in the readings from one test to another with the same LASER. That, in it self, is more important to me than the ABSOLUTE power reading. But that is just me. You guys make your own decisions based upon your own criteria, observations, and/or confidences.