These are worth it just because they look cool. They add incredible function and each in a different way. The two larger ones (halo, and coil) are easily the better functioning one's. The other two work great but are sensitive with water level.
I got this pack as well as a few others, I really like my stax set. It isn't the most flashy when it comes to design, however it makes up for it with complete custom builds of any size any combo. My piece put together is over 40 inches, super smooth with a lot less drag than one would expect from something that size. By far the best part however is putting it all together when someone new is watching. It does get dirty quick but since it all comes apart, and I invested in some quality cleaner, it shines like new in no time at all.
My over all experience ah well, they work very well but u have to OK with cleaning rather often. I was hoping I could by the way get my plug for the base piece I purchased it wasn't in the packaging