Matt,
Thanks for the answer.
If the datasheet should be clear and according to the information you provided - and it should, then the update rate specification ought to have the wording:
Maximum output update rate: Min 125 MSPS.
and not the wording:
Output update rate: Min 125MSPS
as this literally says that the rate should be minimum 125 MSPS, which is wrong. Its the maximum rate which is restricted.
br. henning