Handoff working but no continuity of partially entered texts in iMessage
I am using Yosemite and iOS 8.1. I also have handoff working - and it appears to be working correctly - for the most part - but I am questioning the handoff behavior with iMessage (the issue occurs whether I am handing off Mac to iOS device, iOS device to Mac or Mac to Mac. For example - I can begin composing or replying to an email - and I can hand it off to a Mac or iOS device - and my partially composed email or response shows up on the the receiving device - as expected. However - if on an iOS device or Mac - I begin composing a text message (whether via iMessage or SMS) - I am able to hand it off to another iOS device or Mac just fine - but all the handoff does is open the conversation in Messages (for the correct person) - but does not include my partially composed text from the originating device. Am I doing something wrong - or is handoff functionality partially limited by the devices/Macs being used.
In my scenario my (compatible) devices are iPhone 5, Late 2012 27" iMac, Late 2012 MacMini. My non-compatible devices are Mid 2010 15" MacBook Pro and an iPad 2. I have signed out of iCloud completely everywhere and re-setup iCloud - but the Messages behavior remains the same.
Is anybody else having these issues? Unfortunately nobody in my circle of acquaintance has handoff working - so I can even check.
~Scott
iMac (27-inch, Late 2012), OS X Mountain Lion (10.8.5)