One lost feature of hosted exchange is public folders; if you use these at all you'll have to consider whether you can give them up or not.
The pay monthly licensing of 365 allows your business to be flexible to staffing changes without big cashflow impact but as with most small businesses they will run software until it is no longer supported to get the most value from it. This 'tactic' works for the most part and will give long term savings.
With any hosted service you are essentially signing a perpetual agreement, either you continue to pay or you lose access to your data/service.
From an IT career point of view I consider it a side-step followed by a step backwards. Yes, you gaining knowledge in hosted services but at the expense of hands-on, big-boy stuff.