When using the default one page checkout (checkout1.aspx), I was able to modify the output to show estimated delivery time in the results in InitializeShippingMethodDisplayFormat.

Code:
if (shipMethod.Name == "FedEx 2nd Day" || shipMethod.Name == "FedEx Standard Overnight" || shipMethod.Name == "FedEx Express Saver")
                    {
                        shipMethod.DisplayFormat = string.Format("{0} {1} <small>(Estimated arrival: {2} by 4:30pm)</small>", shipMethod.Name, freightDisplayText, shipMethod.DeliveryInfo);
                    }
                    else if (shipMethod.Name == "FedEx Priority")
                    {
                        shipMethod.DisplayFormat = string.Format("{0} {1} <small>(Estimated arrival: {2} by 12:00pm)</small>", shipMethod.Name, freightDisplayText, shipMethod.DeliveryInfo);
                    }
                    else if (shipMethod.Name == "FedEx First Overnight")
                    {
                        shipMethod.DisplayFormat = string.Format("{0} {1} <small>(Estimated arrival: {2} by 10:00am)</small>", shipMethod.Name, freightDisplayText, shipMethod.DeliveryInfo);
                    }
                    else
                    {
                        shipMethod.DisplayFormat = string.Format("{0} {1} <small>(Estimated arrival: {2})</small>", shipMethod.Name, freightDisplayText, shipMethod.DeliveryInfo);
                    }
On the Vortx add-on, I just see where it calls the following but I don't see any way to customize it like I had previously. Any suggestions from those who have used this add on?

Code:
PanelError.Visible = false;			
ShippingMethods.DataSource = shippingMethods;
ShippingMethods.DataTextField = "DisplayName";
ShippingMethods.DataValueField = "Identifier";
ShippingMethods.DataBind();