I read that the dash command reduced the amount of time it took for the transaction and also reduced the cost of the transaction itself.
Where did you read that ? Dash normal transactions are depending on proof of work confirmations, regardless of using GUI or commandline i think. Although i can imagine a transaction gets created faster through commandline then through GUI, but then it still needs to get confirmed.
There could be a difference in calculated transaction fee between GUI transaction and commandline transaction, i think i read that too somewhere.. cant remember where and if that is true indeed.