Just my own, .02 worth, tws, but personally I don't like using full sinking lines for MetalHeads. You don't say, where you're from.......(thus,what size/type rivers you Steelhead fish in),but I fish the smaller, fast moving, Oregon Coastal streams for Steelhead and a full sinker gets down TOO deep, and would take my line down into the rocks and debris of the stream bottoms. That and I have no "feel" with a full sinking line, when I need/want it.
Full sinkers are also, nearly impossible to do any "mending" with, naturally, because all of your line is underwater, at any given time.
Instead, I'll use a sink TIP line, of varying depths, (i.e.AirFlo's Multi-Tip fly line), and then adjust accordingly to the water levels and whatever reading the water tells me. I can, also, switch from sinking, to floating, in about 60 seconds if conditions warrant the change.
I think your new line is great, for lakes and such as you pointed out. But it will depend on where YOUR fishing for Steelies, as to whether or not it will work well, I suppose!?!
As to its construction.... I believe, (but someone that owns one, will hopefully correct me), it's simply a clear, polymer line, with micro lead or tungsten dust embedded in it's core
Saint Paul-"The Highly Confused"
You cannot do a kindness too soon, for you never know how soon it will be too late.
-- Ralph Waldo Emerson