V14 (v1.4 or WAUTH-2) implementation seems to work well.
No disconnections, composing works, sending and receiving chats (text + images) has been tested. More test is needed for group chats though. Notifications are not properly handled by now but they are answered. Group interface seems to work after the upgrade.

Seems they removed ping/pong, weird. Save bandwidth?

Need to implement: contact status query, image upload (did it change?), group updates triggered by notifications, etc.