Ah, the old conundrum. just been through this myself. What you are looking at is just old fashioned silver rope. cheap and fairly strong, although nowhere near as strong as dyneema. Are you sure that quoted b/s is correct? here is a post which lists them all, and IMO, it is accurate. Go down to post #4 http://www.ausfish.com.au/vforum/sho...=1#post1388140
12mm silver rope is about the same as a good quality 8mm nylon ( not PP) double braid. And dyneema is far stronger again. You'll need a bloody big drum winch to hold 150 metres of 12mm. I've just bought a Tuffwinch 240HC, 300mm drum, which holds 120m of 8mm nylon DB. This will fit on easily, and I'll likely have 30 metres of 5mm dyneema underit, then a heavier topshot of 20 metres or so for abrasion resistance. This is what worries me most for the smaller diameters.
You know there is an alternative to drum winches if you don't want to be limited by the drum size. A horizontal gypsy type is limited only by the amount of rope your anchor well can take. As long as you have a deep well ( wide and shallow is no good) you can just keep piling it in. BUT there is a catch ( knew it, he thinks ) and that is that the only rope which works well with them is plaited 8-strand nylon, and it is expensive. And you need a specific size, can't go thin and save money. I have a Maxwell HRC 6FF on the boat which I am selling ( have sold, just waiting on money) it's an absolute brute, very powerful, but I was always a bit limited by the depth of my anchor well. (500mm)If i only wanted to run 100m out, fine. But if I wanted to get near the 130 metres I had, it would often just pile up a little high right near the end of the retrieve, and just spin the wheel. Just a matter of sticking your hand in the well and pushing the top off the pile, but it was annoying.
I think that if you get a winch that will hold 150 metres of 12mm rope, you'll be paying a lot more extra for the winch than you would have by going to "expensive" high breaking strain rope with a smaller winch. If the thinness worries you, have a heavier topshot for abrasion resistance.