TURN 1 UMI
Odds of getting MM'd: ~28%
Odds that dying when getting MM'd: 85%
TOTAL ODDS OF DYING: 24%

TURN 2 UMI
Odds of needing to Umi: 64%
Odds of getting MM'd: ~25%
Odds of dying when getting MM'd: 80%
TOTAL ODDS OF DYING: 13%

So turn 2 Umi is worth it if you have time (which you often don't)