I am going to add the PBKDF2 strengthening and fix the problem with the PKCS#7 padding mentioned in the article. We plan to submit the 1Password update by the end of March.
The support iOS 3 and the old devices really hurt us there as the performance gap between iPhone 3 and iPhone 4S is huge and so far we were targeting the lowest common denominator. I am still not sure what to do about the older iPhones. We'll probably try to adjust the number of PBKDF2 iterations based on the device. Unfortunately, the PBKDF2 calibration API is only available on iOS 5.