First time poster but have been viewing the forums for a while
Well done on the purchase mate. Just clocked over 20000km on my lpg sv6 and it hasn't missed a beat, you will love it. Also have the same options as you.
My average is 13.1l/100km with a mix 75% freeway (110km/h) , 25% city (60km/h), although it gets a run through the hills every couple of weeks which wouldn't help my average! Im getting about 600km out of a tank by the time I fill up.
Also if you interested in it being a little bit more responsive, I found filling it with an lpg available at supagas, which is 100% propane instead of a mix of propane and butane. It doesn't help fuel economy (you will average about 1-2l more per 100km) but I find the car feels a lot more responsive than on ordinary gas. Its also cheaper per litre as well.
Also remember to apply for the government lpg rebate!
All in all happy motoring mate, im sure you will love it!