Bukkit

Q: When i fly from blue gel block or aerial faith plate, velocity is not always the same.
A: Unfortunately, this is bug in minecraft physics and we can't do nothing about it. Just make sure that when you step on faith plate, you will not always land on the same spot. Sometimes you fly farther, sometimes not.

Q: I edited config, restarted server and config reverted back.
A: Either edit config after shutting down server or use /portal reload command to reload your config.