It's not just the stipend (which is worth about 7-8 Dollars per month I think?) It's mostly the ability to play with all customization options and no more restrictions and caps then we have now.
You can't translate the biggest restrictions from CO (freeform heros) to STO 1:1.
SO it will be interesting what the limitations will be.
Possibilities:
No mix and match of career and ship class
no alien creator, just preset aliens like Vulcans and Trill
Maybe a bridge officer cap of 6. Just enough to man every console on the biggest bridge.
no foundry access
only standard Cryptic original uniforms
only type 8 shuttlecraft/runabout access