Hello,
Upgrading SmarterMail has never presented a problem for me in the 10 years I've been using SmarterMail. If competent IT staff performs the upgrade and understands how to configure IIS the upgrade should be relatively easy. Seeing that version 16 is still in beta and the interface is a significant departure from previous versions, I'd recommend upgrading to version 15 only for the foreseeable future. There are a number of options available regarding contact sharing. Using ActiveSync is probably the best choice for mobile users. A domain administrator can enforce a signature on all outgoing messages.
Matt