mirrorview cascading

Hi

i want to migrate data from a CX4 to a VNX 5700 but  they are no connected into the same SAN and i need to use a Thirs CX.

the plan is :

-> doing a ICSCSI mirroview betwen an CX4/240 -  (Flare 30 ) and CX4/480

-> with the target  on CX4/480 doing a FC mirrorview  with the final targe , an VNX5700

so my idea is to do this mirrorview Topology

Source(CX) -----> Target( CX)/Source  ---> Target VNX

do you have some experience about that ?

thanks