I have 2 Yamaha ns-a838, and 4 Yamaha ns-a638. There are currently just capacitors inline with the mids and tweeters, an inductor for the woofer on the ns-a838 and nothing for the ns-a638.
I had intended to simply upgrade the capacitors with Dayton's. I don't expect a huge change with this upgrade, however, I question if the sound quality would be drastically different if I were to make a crossover. I have no intention of replacing the original drivers. My system is used 90% for gaming, 10% for music.