@ karlink_genius the one concern you 'might' run into using 1000Base-T SFPs "was" the physical size of the SFP, seeing that an Ethernet cable 8-pin connector is larger than LC/SC type of connector for fiber. Therefore 'older' 1000Base-T SFP would physically have issues being installed next to one another, 100% due to physical size. Now, these SFPs could be "sort of forced" in, but NOT A GOOD IDEA. Therefore on any fiber switch, the number supported was max number of ports divided by 2. Could not be installed at same time on either up/down ports/interfaces or side by side ports/interfaces.
The good news is that the industry has made recent improvements in this area. Please note that Juniper themselves do not develop their own SFP optic devices, these come from 3rd party vendors; same situation for almost all switch vendors. The newer versions are smaller, and therefore the physical limitations are no longer a concern.
Any new optics purchased from Juniper, will/should be of the physically smaller variety, with the bottom line being that with this variety of optics all interfaces/ports will be able to support max port count of 1000Base-T SFP optics.
This limitation of max ports/interfaces divided by 2 for 1000Base-T SFP usage was called out in Juniper documentation, althought might have been confusing if this was a SW/hardware/product limitation (answer is no) but instead was just a physical limitation.
Good luck, and HTH.