I have the G900I and here's what I did to get around the locked dock.
Root the rom using cf-root and modify the following.
Open the /system/csc/others.xml file and change TRUE to FALSE on the following line:
And while your at it, to enable gallery auto rotate after root, do the following in the same others.xml file
"<CscFeature_Gallery_AddAutoRotationIcon>TRUE</CscFeature_Gallery_AddAutoRotationIcon>" and change TRUE to FALSE.
Save your changes, reboot
As for using another rom, I'd wait until development is churning out lots of rom variations.
Sent from my SM-G900I.