If you sell at 30c, you only get 20% return.
Initial cost: $20k for 50,000 shares
SPP: $5k for 50,000 shares
Total shares: 100k
Total cost: $25k
Sell all @ 30c: 100,000 x 0.3 = 30k
Gain is 5k, 5k/25k = 20% for $25k.
But if you exercise both options and sell all together at 30c your gain will be 39.5% for $25k + ex. cost