I have just replaced the MT410G with the KTI SA2G. The KTI is smaller, cheaper and has a longer battery life of 10 years vs 7 years. Also came with a mirror and whistle. Bought mine on-line.
Registered my new one with AMSA and marked the old one has having been 'disposed' of. The battery was 7 years old, so out of life. You can get them replaced by GME but they only give a 1 year warranty, so it was cheaper in the long run to buy a new one.
It was easy to remove the battery pack from the MT410G and deactivate it, all ready for recycling. Batteries can be handed in to Battery World for disposal (or you can hand the whole item to them for disposal, for a small charge).