Usually when reeling out line, problems usually occur because of the line reel, the way the line has been loaded onto the reel or the way the line has been laid. I used a lot of polyprop line in my day and properly handled it works fine. Some tips:
a) Have a line reel with a BIG hub. Polypropylene line can't be bent through a small radius without a semi-permanent effect. If the middle of the reel is too small, the last bit of line acts like an enormous slinky toy and is completely impossible to use or even downright dangerous. You actually lose very little capacity by making the middle bigger, because the first couple of wraps only hold a few metres if the reel is too small in the middle.
b) don't be tempted to load absolutely as much line as you can onto the reel. 90% of dives you don't come back with an empty reel anyway and if you need to reel back in, the line always takes up more space. A overloaded line reel that bursts apart mid-sump is obviously a potential nightmare. In particular, don't load try to load the reel really neatly (as a machine would). If the line is in a seemingly neat order, this means a strand can easliy dig down and jam the reel. If the reel is a bit less "well ordered" this doesn't tend to happen. Capcity is a bit less, but if that can save problems handling the line underwater it's usually worth it.
c) Always reel in as soon as you go back or otherwise make the line slack. Imagine that your last line belay is a fish you are trying to land and you get the idea. A small tension keeping the line taught solves a lot of the problems. If the line begins to pull around corners etc..... then it's maybe time you thought about another belay.
d) Remember that you are working in three dimensions. There are aften just as many line belaying possibilities in the roof as the floor, but you are maybe not seeing them (a cave diver swimming along looks naturally down at the floor). A line which sinks is convenient for belays in the floor, but a line that floats is just the thing for belays in the roof. A line off the floor doesn't get stuck in silt, but a lead weight can be used even if there is nothing else available and necessarily belays the line on the floor. Basically what I'm saying is that there is no "optimum" solution, you have to try a few different ideas and see which works best for you in a particular circumstance.
An advantage of the typical 4 or 6mm polyprop line is that it is hawser laid and therefore easy to feel underwater. Most nylon line I have seen is braided and doesn't give anything like the feedback through a wetsuit glove. Another advantage is that it is cheap. But come on, cave diving is a dangerous and relatively expensive game - dying because you were too cheapskate to buy the right line seems a silly way to go. So if you just don't get on with the cheap stuff, spend the extra money and get something you are comfortable with.
Reflective lines.....when the sump is liquid shit, you are navigating by feel, not with your eyes. Rule number one in any sump with less than perfect visibility is KEEP HOLD OF THE LINE.
Safe diving,
Mark