Tre handset question

[johnacraft]

The Tre offer page says:

"In order to use 3's W-CDMA network you need an UMTS W-CDMA/GSM dual-mode phone. 3 ITA u-simcards will not work on GSM phones due to a software limitation made by 3 to avoid excessive roaming costs. All phones bought with 3 ITA are locked to their network, most of them are also locked to the sim-card sold with the phone."

I have a Motorola V3X that is branded for 3, but which has been updated with unlocked firmware ("flash") and unbranded software ("flex"). Does anyone have any insight on whether this phone would work as-is on Tre?