In my experience with any ball valve some are better than others. But they all cause some level of flow issues. If i have to use them i love full port valves as there is less geometry versus other types of ball valves. I personally prefer butterfly valves. Unless it is a major issue to your setup i think most of us just ignore that part.
Update: System ran great for two batches this past Saturday. I don't know what my issue was, but it is fixed. I had to throttle back quite a bit to keep the output from Therminator below 70 degrees. Worked like a charm.