My only Apple product is a macbook that I have for the sole purpose of playing and producing music. I deliberately disabled iCloud and all their associated services. The word on the street is Apple take security seriously, so I'm inclined to say it can be used securely - as long as you're generating random unique 22+ character passwords for each and every account. That being said, I use KeePassX2 on my Macbook (pretty much purely for Soundcloud/Mixcloud logins). The only thing I use the OSX keychain for is locally stored wifi passwords.
My views, when it comes to security software - if it's not open source, it's not even in the running for something I would consider using. I may not have the skills to personally audit the code, but I (and/or others) could crowdfund a campaign to hire professionals to do it. I do not have that option for products that are proprietary, and in my book, Apple's (or any other company's) promise that their product is secure simply is not good enough without proper proof to back it.
Many thanks for the reply. Good luck!