MSD vs down payment

Besides getting your $ back, what’s the advantage of using MSD vs a down payment ?

Those are two separate things, which serve separate purposes. It’s like asking the difference between flying on a major airline vs flying on a skydiving plane.

Each security deposit lowers the money factor, allowing you to pay less in financing costs. You get the money back at the end of the lease or if you total the vehicle.

Down payment is just a prepayment upfront to lower the monthly cost. You don’t ever get that money back, even if you total the vehicle as you drive it off the lot.

My experience has been that dealers of Manufacturers that don’t take MSDs will tell you that its the same and that you will never get your security deposit back. They are just jealous about their inability to offer you a much better finance rate that translates in a lower and competitive monthly lease.