@rccpgm - thank you, didn't know about that:
All Juniper EX Access switches only see Fiber ports when an Optic is plugged in; they all function this way, I believe.
The initial plan was to connect two racks with EX3300 - EX2200 using these modules, and later, after EX2200 replacement, move to 10GE.
I sure will try them in EX3300 - if they will work there at 1GE, I will just put Catalyst to new rack as 1GE solution.