I've been using 6lb WM hi-vis yellow line for 1.5 years and I like it so far. It has much less memory than all the other mono lines I've used. I do have several times that it has knots on my reels in the 1.5 years. But it is not too much, I believe.
As HEAD says, if the line is wet, the line has less memory. I've pulled a 30lb catfish with this line.

BTW, while so many experts are watching this thread, I have a question as to how well braided lines perform in casting. I have two kinds of braided line. They definitely do not have any memory. But I can not cast far with these lines, especially with light bait. It seems to me that the two lines I have tend to have a lot of frictions between coils on the reel. I mean it's between coils. I can hear it and I can see it. I use spinning reels, btw.

I refuse to use braided because i hate the way it feels and I hate the way it drags through the guides. I hold the line in my hand and it doesn't wear very good on my fingers either

Paul and I use Stren Clear Blue and it is just as easy to see as yellow IMHO. If you are fishing jigs, any line will eventually get some twists. Especially if you use those line twisting belly bubbles

stretching the line out (catching big slab crappie) will help the line have less memory . As for braid vs mono I am still on the fence. I recently started using stren 10lb size of 3lb, hi vis gold braid. I have been using it for a few months now, so far I like it. It has zero stretch and zero memory. There are ofcourse some down sides but so far I like it pretty good. I have it on about 6 of my rods. I dont cast much this time of year so the casting answer will have to wait till spring.

just bought my second spool of w.m. hi viz and love it, bought one for my buddy mike and hes hooked too , i also bought the 7 ft pro series rod but that im not too sold on , i think ill hacsaw the butt down then i can use it better for jigging straight down .w/r/j

IMHO, the braided lines are suitable only for backing, HD offshore spinning, or very deep water fishing. Try it if you must but you'll find out for yourself. The grating feeling through the guides, the first graphite rod you break because of an over energized hook set on a short line, the 10,000th time you have the line loop around the tip of your rod and you have to untangle it by hand, or the number of times you cut your fingers on the stuff.

Use mono, change your line often, cut back a casting length if it gets twisted, use reel magic.

winterwang,
I've stopped casting overhand all together. Rather, I shoot a jig regardless if it's 10' or 100'. It's safer (no backcast), more accurate, less work and easier on old muscles. It takes a little practice to be able to get it out there a ways, but you can do it. Try it; I think you'll like it.

I'll be trying the Power Pro tomorrow and I'll let you guys know what I think.