Synthetic longswords cause a lot of emotion, but like it or not, they are here to stay and are the equivalent of shinai. Neither a synthetic or a shinai are perfect sword simulators, but they are safer in some respects and I would claim that the synthetics are more like real swords than a shinai. In fact they are pretty close to a feder in handling, if they are done right. So with this in mind, it is important that we don't look like larpers with home-made boffer swords...
There are of course vital differences between nylon and steel, but the advantages outweigh the disadvantages and training with both
a synthetic and steel is a good thing, I think.