While I can't say I use my line enough to comment on service interruptions (I generally wouldn't notice them, because I don't use my line enough), I'd like to say that IMO your concerns, while not surprising, are somewhat blown out of proportion. Issues like "upstream provider maintenance" are out of voipo's control, and they likely happen with just about every VoIP provider (but they don't tell you). Issues such as "New Database Servers" are more of a concern, as they involve equipment changes at Voipo. IF Voipo follows good change control / network management procedures, changeouts of database servers should be seamless to the customer. It is my opinion that they announce such things to let you know that something is going on in case you have troubles with your line during the maintenance window.

One other argument FOR getting a router, regardless of having only one device connected 'behind' it, is that the router does provide a hardware firewall for your PC. It may be worthwhile for that reason alone, with the ability to connect more devices to your network as icing on the cake.