I Had the XC and it is a great bike, especially if you are coming from a road bike background.
I don't say it is not good at dirt riding, I have done a bit of dirt riding but it was not easy for me as it needs a bit more revs than I was used to (KLR Thumper/low revs) on and I do not like revving things to perform off road if that makes sense. Yes the trip has loads of torque but it still needs to be revved to get the power down.
I got it sideways on occasional and even 180degree which was unintended although my son though I was cool

Very light handling (my reference)
The bad: The service agents at Kawasaki (where Triumph is based) was a painful experience, and expensive. I did not suffer the 'common problems' on mine but sold it with low km's.
Stepper motor that got dirty and then the bike is very temperamental (probably because I did not ride it hard on dirt)
XCX is nor ride by wire and do not have the stepper motor.
The starter motor gave problems on most and I have read still do.
The biggest concern is the valves that work into the head - this happened on the Daytona and street tripple and then high mileage XC's. I was at Pretoria North bike tyre which is also a bike workshop and the mechanic showed me what happens. This is normally anything from 70k km up. Very expensive fix this one, and I do not know if this is fixed on the XCX and the new range of 765 Street tripple motors that has recently been launched as upgrade to the 675.
The 800 XC motor is based on the Street tripple - just reworked for more torque.
I also do not know if you can prevent this with regular valve clearance - but they told me that you need to drop the motor to set it....and that ads labor cost.
Then to reach the Air filter you need to remove the tank - now I can do it and did do it but it if you are not technically minded I'd say don't go there.
There is also a pre filter (a must!) which helps.
Still, nothing in the class beats it for power, sound and pure joy. If you have a good dealership near you and enough money for the services why not? This is one bike you buy with your heart.