Tried it today:
VNAV CRZ speed was ECON (.791) and I selected a VNAV DESCEND target speed of .760/280 in the DESCEND PAGE.
After executing DES NOW on the VNAV DESCEND page it decelerated to .76 in a VNAV PTH descend with 1000fpm.
After selecting the cleared level in the CRZ page it stayed in a VNAV PTH descend ( FMC showed CRZ DESCEND ) but started accelerating to ECON CRZ speed.
Not sure if this is the same for all updates (think we use 10.7).
Long story but it proves my earlier thought to be correct.
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