I'm currently finding myself in a bad situation. A customer has Outlook 2013 and is connecting via IMAP to RackSpace email (non Exchange). After their recent upgrade to Windows 10, they discovered that IMAP wasn't syncing things correctly back to RackSpace. They lost all of their sent mail and several people lost random stuff from within folders. It's a very bizarre situation.
They are looking to leave RackSpace now and move to Hosted Exchange/O365.
It wasn't a bad email client overall though. It seems to me that some sort of generic web based email client akin to gmail would be neat. There are things like it, but none fully support multiple mailboxes equally like Thunderbird.
Nylas N1 is interesting and just added that feature a month or so ago.
I haven't tried letting all of that stuff connect on my Android device.
Does it allow the use of your real phone number, not a google voice number?
You can text from your phone with your real number via Hangouts but not from your PC. When you SMS from your PC with Hangouts, it always uses Google Voice. Your phone just uses the last number that sent a text to the number your text as the source. You can switch back and forth and Hangouts aggregates it all into one thread in Hangouts. It's nice.
The other side could be confused though if they don't have your google voice number in your contact, or worse, it can't aggregate sources.
Hangouts goes by contacts, so if you have someone who had 17 cellphone numbers and you had them all saved in your phone under one contact, all texts would be aggregated into one conversation. But yes, if someone doesn't have an SMS client that aggregates, it will make your texts via Google Voice and texts via your cell number as separate threads.