If an organization with 45% of the hashing power became malicious, it would be able to "double spend" 2 confirmations approximately 20.25% of the time. (the other 80% of the time, the 55% side of the network would "catch up").

For an organization with 45% hashing power to maliciously double-spend cross 20 confirmations, it'd have to win the coin flip 20 times, or 0.00001% of the time.

Methinks the faster hash rate is strictly better from a security standpoint... especially when you consider players who can perform a near-50% double-spend on the network. (A large 30% player may go for a "double-spend" within 2 confirmations, and will be successful 9% of the time)