Looking at a Hitachi ZX 240 don't have any knowledge about these machines it has 8000 hours one question I have is how well will it start below 30 degrees also the good and bad thanks
We run a 06 270. Same machine just a little bigger. I wouldn't be concerned about the hours providing its been cared for. As far as starting they'll start down to -30C without to much trouble so if you're talking +30F you'll have zero worries. Emission stuff on them is a pain at times. Mines throwing a code for the egr valve. Has for a long time though so I'm not worried about it for the time being. Injectors can be a problem. Ours has had a set out in every 2500 hours on avg. the earlier 4hk series had some programming problems. They were cracking pistons but that has been fixed as far as I know. Our motor was actually rebuilt because of this problem. I like the machine its quick smooth and strong. It's pretty good on fuel haven't actually measured consumption but running it flat out it'll move a pile of dirt on a tank.
I spent nearly 5000 hours operating a 2006 240 long stick and had no problems at all starting to -28/-30c, which was the coldest we would operate them in. At the temperatures the OP is talking about there is nothing to be concerned about. Fuel consumption in hard digging, I found to be considerable, at around 9 US gallons/hour ripping and excavating sewers and basements. But they do move material, as I would average about 2.5 to 3 hours on an average size home with a roughly 6'cut, keeping it to within about an inch on grade. If it's in good shape and reasonably priced I would highly recommend it for consideration.