In the middle of switching now. Obvious pro is saving money: we are getting 6x the speeds for half the cost. Our previous contract was five years, and five years ago 50mb was great. Now we are bumping up to 300mb on a three year contract, and can readdress then if needed.
Cons are its a PITA to change all our public facing IPs. We have about 50 total IPs to change routing and firewall info for. Not hard, but time consuming. Email, website, sharepoint, VoIP, CCTV, alarms, etc all have to change.
But in our case it's worth it. Just document everything so your change is seamless.