These kind of questions usually spur arguments and debates, but....
I have V7R2 right now and will probably stall V8 until they don't give me a choice - V8 does add functionality and some new capabilities.
Cisco tends to lock you down in expensive service contracts that are not necessarily optional. With Unify they usually try to get you to at least have a software update subscription but they won't force you into a service contract otherwise, but T&M can be expensive. We have Unify SWA and a minimal contract with Black Box that provides remote monitoring and anything they can fix remotely without dispatching a tech, plus repair parts exchange. I do everything else. If they have to dispatch a tech it is T&M but the rate is reduced because of the contract.
Upgrading Cisco systems (has been in the past) is difficult because you can't just upgrade part of the system if it is really spread out. If you are doing an upgrade you tend to have to do it all the same night or you will have assorted system issues. They want you to regularly keep it up to date. Unify doesn't care if you keep it up to date for the most part, BUT, if you do not keep it within about 3 versions of current and you have a problem they will make you bring it up to current before they will look at it. If you later go to buy a contract they will make you bring it up to current before the contract starts. There are people out there still running V5 ad it's doing just fine, but there are few service options unless they go with a third party provider, and even they will not have access to Unify support for that old of stuff.
Cisco tends to want you to keep all your network switches, routers, etc, up to date as well, which is a really good idea for security purposes but can really be a hassle if your place runs 24/7/365. If you start to have problems and ask for help they will like to blame it on your network hardware not being up to date.
Cisco might be easier to hire techs that are experienced in managing those systems. If you want someone with experience on the 4K you might have to look harder but they are out there!
We have been with Rolm/Siemens/Unify/Atos since 1984, and usually our experience is the stuff just sits there and runs. You're always going to have failures in any system, but these have proven fairly reliable and somewhat easy to maintain - espcially if you take the online BACKUPS course they offer at Unify Academy - it will show you about 6 or 7 fairly easy ways to have concrete disaster recovery on your system for not a lot of money (cloning HD, scheduled backups of remote shelves, off-site backups, snapshots of all the system data, how to pull your system recovery files off the processors, etc.
Don Bruechert, Voice Comm Analyst II
CareTech Solutions @ Holy Family Memorial
Manitowoc, WI, USA