I personally think if you plan to settle down here for good then it would be a good idea to invest 2-3 years of your life into a ID program. It has lots of advantages. Not only will it help you built on your existing knowledge in dentistry but it will also help you get integrated into this system of health care which is different from that of your home country. This exposure will help you improve your communication skills and eventually will help to understand your patients better and will prepare you to meet their expectations. As insignificant as it might seem right now these qualities are very important to be a successful dentist.
The 2 yrs that you invest here will give you some room for error and you will eventually become very confident in your preformance. Right now you possess the skills to be an efficient dentist but lack experience in various other parameters which will effect your success if you decide to practice here. I am not saying that you would be unsuccessful but you will face lot more resistance. You will find yourself explaining most of decisions and treatment plans not only to your patients but also to your peers as you will not be considered an 'equal' for most part. And from what I hear there are issues with insurance too. You will be more of a target for a "sue friendly" pool.
Having said that I also want to remind you that this is a ridiculously expensive program and you need to come up with the funds. You might have to take a loan in which case you will need an American ( or Canadian ? ) co-signer to sign for your loan or you can also take a loan from your home country if its a possiblity ( Iam not sure of how that works though ).
Taking the Bench exams will definitely save you a lot of money but if you look at it from a different perspective ie long term goals I doubt if its a good idea. These are just my views.
And another point I would like to make here is that if you are planning on applying to different schools then you will have to do your own home work. It will be in your best interest to get all the information regarding a schools/programs from the horse's mouth. If you rely on hear-say you might miss some of the schools in which you might have had a chance.
