Keep in mind that kit is for the Arcade 1up. For the Legends ultimate you also need. https://www.amazon.com/dp/B083DL4DF4/ref=cm_sw_r_cp_apa_glc_fabc_9B4S71ZTWQX77RTSV66X

As far as hotswappable, it is but you still have to get under the control deck to twist the lock to allow you to slide out the stick and slide the replacement stick back in and latch it.

Edit. I may be wrong that amazon listing says Atgames compatible but it's also the same listing I bought for my A1U that needed the conversion kit. So maybe they switched up the kit and just made it with the longer sticks and use it for both.