I split alot of gnarly maple and apple. Lots of branches means lots of knots. My 22 ton splitter eats them all.
When I was a kid we still had alot of standing Elm trees that got cut as we cleared fence rows, we did it by hand, sometimes we had all 5 wedges stuck next to an axe and a maul and we were wacking all of them with a sledge. Elm would be a good test for a splitter but it's all gone on the East coast from Dutch Elm disease