Hello and welcome to HCM,
or clear braces have great cosmetic advantage, the only commitment you need to give is not to forget the placement of braces atleast for 20 to 22 hours since they are removal if you are comfortable with it consider replacing your metal braces. approach your orthodontist and talk to him about this, there is huge cost difference between the two. you dont need any cephalogram for invisalign so treatment can be completed in short time. i hope that helps you, take care.