Hi!
Sounds like a great trip that you are planning, keep my fingers crossed for you that everything will work out fine and that you will have a great time here in Europe.
Concerning your question, I'm some type of "fresh" XF650 owner, but nevertheless I'm able to compare it with several other bikes which might be suitable for you. The XF650 seems to be a very nice bike with a strong engine and a very comfortable seat position for the rider. For a more or less on-road trip it is definitely first choice, due to the fact that used bikes in good condition are quite cheap here in Germany (if you look at
www.mobile.de for example). Furthermore the bike is quite reliable with simple maintenance procedures to be fulfilled. The only two things that seem to be a little tricky are adjustement of the valves (concerning maintenance) and the sealing of the cylinder foot, which might become leaky after some time.
If you are planning to go more offroad, have you ever concidered about a Honda Dominator RD08? This is quite comparable to the XF650, with the difference that performing maintenance is a little bit easier (in my opinion). The only modification that you might need is a better seat (will cost around 40 Euros and a little time of work). Prices and reliability of the motorbike are comparable to the XF650.
Decision is up to you, if you would like to know more details, please post it!
All the best,
Thorsten