Is Lack Of Italian A Disadvantage?

I am sure that you will be able to cope up quite fine along with all the other people. It will be little difficult in the beginning to get used to their way of living and their language but you will definitely get used to it. Most of the Italians are quite get natured hence you will have no trouble getting along with them.
 
It could be a disadvantage if you go to a market or restaurant and the workers only speak Italian. I had the most difficult time once when I was lost in Milan. I couldn't use my phone because I didn't have an international data plan so that meant no internet access, no Google maps, or no translator. I had to ask people but in this particular area no one spoke a bit of English. I eventually found one person who spoke minimum English and was able to help me though. However, it is best to know the basics.
 
I think that not being able to converse in the native language of the country that you are visiting, is always a bit of a disadvantage. It really helps to have at least a phrase book with you wherever you go, as it makes communication easier. Also, it might be a good idea to acquire a bit of basic Italian online. There are many free courses. or even better, attend Italian classes. :)
 
It is always a disadvantage- you can fall into "tourist traps" and you never feel quite equal with the Italians. The basics are extremely useful, the locals like you a bit more as it feels like that "you tried".
 
I lived in Rome, and knowing Italian was a big plus of my daily life, being able to make informed decisions about the products I buy and chat with the butcher and the kebab guys. On top of boosting your social life, it also opens up the possibilities in terms of lodging and, I expect, work. That being said, since I had a good handle on the language by the time I moved to Rome (for a semester of university), I wished I could practice it more; however, the people I studied with were learning French (my first language) and were eager to discuss with me in this language. Other people around town were also very quick to switch to English if they saw me hesitate just a moment. For this, I would have preferred to live in a small rural town, where people I meet would not even think of talking to me in a language that is not Italian! That would be for sure the best way to make fast progress, I think.

But yeah. If you go, you should learn and practice as much as possible first. Practising becomes less efficient if you don't have a good basis already!
 
Seeing that you plan to live there of course, I would take it as a very bid disadvantage. I would say that you learn the lanuage for sure now before you buy the place there or even go there.