Originally Posted by
BusTrav8yrs
If you are SPG Platinum you don't need to get the DL Silver
If you are registered for Crossover Rewards and are an SPG Platinum elite member, you are eligible to receive Priority Check-In, Priority Boarding, Unlimited Complimentary Upgrades on paid tickets and your first checked bag free in accordance with the SkyMiles Program Rules and the Crossover Rewards Terms and Conditions on eligible Delta flights.
But FOs get higher upgrade priority and can be upgraded at their window, versus SPG Plats only on the day of travel.
Also, DL elites (I'm not sure whether FO is high enough for this) get SPG points equal to DL MQDs for their flights, so if you're elite enough in both programs, you get extra miles/points in both directions even though you have higher upgrade privileges without using crossover benefits for that.