Just wanted to put this out there in the forum because I can't find a link to report issues or provide feedback to their beta version of Messages for Mac:
If I start a message chat from my Mac using the Messages Beta to an iPhone user (sending messages to their phone number) and the user responds, the chat session appears on both my iPhone and Messages Beta. (Works as I expected).
If I start a message from my iPhone to another user's iPhone (send to their phone number) the chat session only appears on my iPhone and not in Messages Beta on my Mac. But, at a later time I send a message to that same person from my Mac, then the chat session sync with earlier chats. (I know that Messages Beta is using only the email address and not the phone number so it would make sense why the syncing doesn't occur...Just wondering if Apple can find a way to use both fields so any messages can be received on all devices whether someone is using an email address or phone number).
Just as a test, I sent one message to a a friend from my iphone using the phone number and they received it just fine. Then I created another message, this time from my Mac (using Messages Beta and the phone nubmer as the contact), they received the message on their iPhone, but it created a seperate session on their iPhone. So they saw two sessions from me in iMessage on the iPhone.
To get the messages to be synced on both my iPhone and my Mac, the initiaing user had to add my email address into their address book object, then create a new message sending it to my email address. (Back to the suggestion above, if Apple can find a way to setup the iMessage or Message system to relate an email address to a cell phone number, then anyone initiating a message can use either a phone number or message from the iPhone and it'll send the messages to all devices).