Thanks riff_raff. I learnt something new.
The ULOR is interesting, though I must acknowledge I do not understand fully by the 'offset'. Anyway, I wonder why boeing did not offer this or the JMR. Could it be because the concept is still too new and there were not enough validation yet?
It is also enlightening for me to learn that the CH-47's vertical separation is strictly not needed but for noise minimisation. The interleaving would have ensured the rotors do not clash.
Back to the ULOR. Can the present CH-47 be fitted with forward thrust fans and allow the rotors to be unloaded during cruise? Isn't the X2 using this approach?