When looking at "investing" into the Ground model you are essentially buying yourself a job.. buying into someone else's system... buying into a one sided locked in agreement... buying into the privilege to do someone else's work.
You have no control on how that is evaluated or any control on measures that affect your "business".
You are basically an employee with business expenses.
There are contractors with cash cow routes, with densities and volume that are turn key in terms of operating efficiencies. You should also remember that you will invest heavily in equipment. Most companies hold large debts to financing these machines that FedEx demands of you.
You should think long and hard if you want to tie yourself to a large company that is only there to control and use you to their advantage. They control who you hire and employ, they control what equipment you can purchase, they control what you wear, they control your pay, your performance, your destiny. Not what I call a true business or partnership. Look long and hard at their overall satisfaction rating from those who have worked for or with them. Look at news and media releases, and look at how they are trading on the market and what analysts are saying. I'd look more to what FedEx has to offer or not offer than the contract you are looking to purchase.