We used a Safari Chiller light last year. I never used the original fibreglass one.
The original fibreglass one is much more robust and durable. And it has better insulation. My experience though was that during a session, the Safari Chiller light kept the bait frozen hard for long enough to get through a session. I am not a big fan of overdoing it, and being on the rocks for longer than 4 - 5 hours gets tiresome. I guess its a different story when you are continuously reeling them in!