I wouldn't worry too much about finding the perfect netcup. They are designed to be at a cheap price point so they will be all very similar. A liner would probably be needed to keep the soil from washing out, so the spacing of the openings are no big deal.
If you converted to a hydroponic TNF system for something other than tomatoes, with smaller root systems, the spacing between openings usually doesn't matter either because you still have a medium, like hydrotron, in which the roots have to pass. The heavy duty is mostly used for something like dutch buckets or DWC where the netpot is taking the load and transferring it to the lid of your container.
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