Assuming Marriott grants you the status match and you complete it, your SPG account should match to Platinum (I did this last year). If you are mattress running 6 nights for the sole purpose of potentially being upgraded to a suite, it is not worth it since the chances are slim you’ll get an 8 night upgrade. The breakfast is a nice offset, but you will likely need more SPG stays through the year to get “value” out of the mattress run.