I guess you can call this a 2-tier rig....but that's okay with me.
My philosophy changed after having a 1-tier:
-Using more height (gravity) to flood the hell out of the march pump. If I want to prime my tubing, it'll be a snap.
-Using gravity to drain the bk through a CFC. I can also use my pump for this, but I don't have to. I used to use a B3 50' 1/2 " IC.
(that's a different discussion, which I can comment on outside of this thread)
-Not worrying about having my HLT higher in the air. It's really well supported by side rails, it's heated in place, and I have a sight gauge to tell me how full it is. I mean, come on....we all know what hot water looks like! It's not that high anyway, but it saves MEGA space being stacked....
-Here's the big one! Not worrying about having my BK in the air! I know some folks may wonder about this....I started using fermcap-s, and now I don't worry about boilovers! I realize I don't need to look into the BK anymore worrying about foam, so now I just toss my hops in and stir. I can still see in the keggle on my toes, so it's not a problem. At flameout, I whirlpool and drain to the CFC. I plan on integrating a hopback that goes on/off with QD's for easy removal.
The advantages? I have a rig that takes up a hell of a lot less space than my single-tier:
I know it's not as pretty, but it does the same thing in a compact, shiny package! I still have my pumps, but I can also use gravity, because it's free!