Its going to be a wait and see thing, but my gut says SSD will be the coveted Tier one.
MFSR seems to be almost walk one late at night.
While a comparison to MK is not totally the same , its fair to say 7DMT is almost never a walk on, even late, while the other big rides that compete with it at MK CAN be almost walk on at certain times.
I have yet to see SSD be a walk on, or even less than 30 minutes, making the 7DMT a good comparison.
Not to mention they are both similar coasters and have loading limitations.