Are there any restrictions on MSB licenses that we should know about?

The restrictions are provided to you by the MSB PLH themselves (Principal License Holder). Depending on who is going to take your case, the PLH will let you know of the prohibited products &/or services that you cannot engage in when you sign up with them. This is inclusive of zones and territories worldwide where you cannot sign clients up from, depending on your flow of funds and licensing outside the United States (or lack thereof).