I can play my canon Shepard over and over to further refine him into the character and playthrough I want.
I've probably done that 6 times
Shoot, I've done it so many times as well.
The SM mechanic was a shot in the foot. Personally, I think it should have had a couple of forced deaths, a virmire-esque choice, and possible deaths depending on who's in your party in the last stage of the mission. And to throw it in, have it be possible for Shepard himself to die. Since that save won't import anyway, there's no point not making it since it is a Suicide mission. That way, certain characters can be uploaded into ME3 with a stronger probability of relevance to the plot.