On one hand they same like great inventions that increase comfort in a dive. On the other hand, it seems like adding an additional potential point of failure to your kit.
Been looking at the Omni swivel as an add-on. Cheaper brand reviews mention leaks, but Omni has positive reviews.
www.scuba.com
Been looking at the Omni swivel as an add-on. Cheaper brand reviews mention leaks, but Omni has positive reviews.

Omni Swivel Standard
Omni Swivel is dedicated to manufacturing the finest and highest quality diving products on the market. All of Omni products are made in the USA with over 40 years' experience manufacturing diving...