Anyone ever use a Sinker-Dropper?

I thought it was kinda a cool idea but there is no way to retriever your sinker after it is released.  I am kinda wondering how they can sell it especially since states are looking at banning fishing stuff that has lead in it and there product litters the bottom with lead sinkers.  Anyways I was thinking that if you used something like this with a large weight and run a hand line down tied to the weight when the fish bit the weight would drop off and you could reel up the fish then when done you could pull up the weight.  Being not so experienced in the kayak fishing category yet I was wondering what you guys think could this be a poor mans solution to down-riggers?
www.sinker-dropper.com

 Drop sinkers have been used for years for salmon trolling. With the cost of lead these days it can get expensive dropping them on the strike. Before downriggers became popular guys used to use sash cord and sash weights to get their gear deeper. They'd tie a single knot at say 20', a set of two knots at 40' a set of 3 knots at 60', etc. It worked but downriggers are far more efficient.

What if you made your own weights out of concrete. One 25lb bag could go quite a ways. Just make a couple of different size molds. Much like pelagic paddler's "bag of rock anchor"

don'tdisstherockbaganchor. it simply works

What if you made your own weights out of concrete. One 25lb bag could go quite a ways. Just make a couple of different size molds. Much like pelagic paddler's "bag of rock anchor"

It would work fine, the only problem is concrete is not very dense (compared to lead at least). Your weights and the drag they cause would be huge! Heck, I don't even like using steel weights because they feel too big.

don'tdisstherockbaganchor. it simply works

No ill thoughts towards bag of rocks anchor here. I plan to build one of spots F'n'D drift anchor rigs with a bag of rocks on the end.

I thought about the density issue too. No doubt that you would definitely need a heavier concrete weight to replace lead.