This thread is mainly about updating MRT transponders that won't reliably work with the new AMB decoder track system, to a newer MRT that will.

I agree there is little need to send in a perfectly good AMB, as those still work on all decoders. Well at least for now, some are concerned about future AMB upgrades, and might take the opportunity to update at reduced cost, just in case. Or perhaps for damage like ta man mentioned.