only for 10 sec every minute, means the sam still more interesting most of the time, since this 500 dps of difference is all the time.
If we take the 500 dps number you give it means the ninja get the same dps of the sam for 10 second, while the 50 other second the sam have still 500 more dps... plus the dps of the sam is too boosted for 10sec meaning he get ahead all the time.

people are plagued with the utility curse recently, forgetting to look at the whole picture. a lot of people think that raid is only a question of number or utility... sadly it's not like this, it's role over all. you will bring 2 tank, 2 healer, 1 support, 1 ranged dps, 1 melee dps and if you can... a main dps. someone that will have as sole goal to bring enough dps for cover for the support dps that have generally a dps subpar.

SAM like MNK have this role and seriously a raid leader don't concidering this will shoot in his feet.