As Heart said, it's something else I've raised here as a question.
You say with a rainbow body it's easier to help many beings. But if one dies the flesh and bones are left behind and there is not limit for emanation bodies whether one has a human body here or not. That's why I ask what extra rainbow body has.
hi, for great beings who attained buddhahood, there is no limit for their emanations.
Just give two examples of 'Powa chenpo' rainbow body:
Padmasambhava and Vimalamitra; they all still have endless emanations to help beings. But for this world, at this time, they don't need to go through common body old and death process.
Like Padmasambhava, he stayed in India for hundreds of years, and again stayed in Tibet for a hundred or so, in the end he didn't die, he went to raksha island. Vimalamitra is still in Mt. Wu-Tai in China now, quite some Tibetan masters went there and met him in person (in forms of begger etc).
Although fully enlightened beings can generate limitless emanations anyway, when in form of klesha body, their actions are usually limited by natural rule: old and death. Even when there are some ways to prelong one's life, usually a flesh body can't be used for too long and in the end one can't be as active as young people. Therefore, great beings change body, that's one of reasons why we have tulku system. great being himself won't be influenced by that process, and for some people it's not a bad thing to remind them that nothing is preminant; however low-wisdom people like me would sometimes think how nice if dligo khyentse rinpoche or dudjom rinpoche didn't need to change their body!
It's just my opinion, actually not too many people really attained powa chenpo body in history anyway. So if you prefer mahamudra, there is no problem to follow it.
This kind of discussion is interesting, but is also like two ants debating about which skyline building is higher. Don't spend too much time on it unless you are already near the top of one of them.