Welcome to TFP!!
I'm gonna assume that we're talking about flexible pipe (termites can't eat through schedule 40 pvc, rigid pipe). The black stuff is called "black poly" and the flexible pvc hose I just call "flex pipe".
The black poly is resilient and much less likely to burst from ice forming in it. The downside, to my way of thinking, is that connections are made by heating the pipe and inserting barbed fittings which are secured with stainless steel screw clamps. It's the clamps that can cause trouble, underground, they will eventually rust out and cause a leak. Also, some cheepskate PBs use flimsy fittings which eventually degrade and leak. It has some 'bendability' to it but not as much as the flex pipe.
The flex pipe (Tigerflex is the big name brand) can be glued into regular pvc fittings (I prefer the chemical/ mechanical connection of glued fittings over the just mechanical clamp connection). Of course the downside is that termites will chew holes in it if your yard is infested and sharp rocks that heave up as the years go by can puncture it. Also, if above ground and exposed to the Sun and elements, the flex can quickly take on a diseased look - the pipe is still good, it's just splotchy and ugly. Flex is more expensive per linear foot than rigid pvc but comes in 100' rolls, so you don't have to keep coupling sections of pipe together every 10 - 20 feet, also, the fact that you can easily bend it means less 45* or 90* fittings.
As for whether or not to replumb the pool, I'd have to say no - if it ain't broke... I would wait to replace the pipes until you have to because you're loosing water (there is an article on Leak Detection in Pool School). Keep an eye on your water level and if you ever suspect you are loosing water, try the stuff in the article to determine the probable cause of the leak and we'll help you from there :-D
I hope you have nothing but a Trouble Free Pool this season!
