Dislikedexpect to open real account in a couple of weeks so...
downsides to it?Ignored
you a a bit right - Interbank Rates do have a specific price rule - they do not quote prices below one million order size - therefore it is not possible to do that with a typical online BROKER - as they mostly do have not more than 3 or 5 Bank-Connections - which mostly are no real Interbank Dealing Desks as well. Former days minimum 500'000 USD to open an account with - nowadays some do with 50'000 - but not less...
Moreover - a Dealing Desk is not a thing wich is operating against you...
Mostly they give very good advice and help - and you can learn a lot from / with them. They give you sometimes a phone call - and they do give you quite good hints sometimes...
It is an error to think - that they do have fun to operate against you... ! ! !