I don’t have experience with the particular 7 ton splitter you are considering, but I have used a 5 ton electric for years. It split most of our wood in Virginia, but it had its limits. With huge red oak rounds, my husband had to split them with a sledge and wedge before the splitter could handle them. (They were also huge enough that we had to split them anyway to move them to our trailer since we were scrounging wood in a nearby neighborhood, and we couldn’t move the rounds otherwise. I think he had to split some of those big quarters even further for our splitter, though.). We split lots of oak with it as well as some hickory, cherry, beech, maple, and pine. I would expect 14 inches in diameter and 16 inches long to be no problem. If something doesn’t want to split all the way at first, we occasionally shift it and find a better spot. Overall, we have been very happy with the relatively small investment we made years ago. It can’t do everything, and it’s not super fast, but it gets the job done within reason, and is nice and quiet. Even some of my children have been able to help operate it.
We now live in Texas and burn most of our wood unsplit because it’s not huge and it seasons very quickly in our heat and storage conditions. Our splitter still works fine, though, and gets put to some occasional use. Recently, however, it quickly hit its limit on Live Oak (the species Quercus Fusiformis). It’s just too dense, and my husband couldn’t even get a start with a sledge and wedge. We don’t have enough Live Oak that large (which isn’t really very large-it’s just the grain) to make it worth a big investment in a more powerful splitter. For those pieces and the awkward knotty cedar stumps we sometimes cut, my husband can noodle the pieces into stove size for us with the chainsaw. That might be an option for you if you occasionally get wood that a small electric splitter can’t handle.