Most impulse sealers use a very thin wire, so the actual sealing area is very narrow. I always double seal when I use mine. Plenty of them on E-bay.
Plyban can easily be sewn as well. You can use an impulse sealer to make the basic cylinder and then sew a circular bottom on. HOWEVER, I have done that and you get a wicked seam that shows up in the pressed cheese anyway. You will get better results if you just put a loose circular piece in the bottom of the mold and use the cylinder. Plyban can also be heat molded, so I would like to find a way to mold a lining similar to a Kadova mold. I have never had anything stick to Plyban, so I would prefer that to the stock Kadova lining, even if it had to be replaced more often.
I would never go back to cheesecloth.
I am looking for a wholesale source for vacuum bags if anybody knows of one.