Well - I am type two and I have a big trampoline in the garden so rather off track - but it is useful as it is something which is handy and fun so more likely to be kept up. It is low impact on aging joints, it makes a good surface for practicing yoga or doing stretches and it increases strength and balancing ability, improves flexibility and stamina - and it is right that it is good for singers - also beneficial when constipated.
With a rebounder being smaller it might not be good for somethings the big one can be used for, but with being small enough to use indoors you get the benefit year round and I have to wait for the good weather.