I actually have both of those lines for my 9' 9wt.
The sly line is relatively new to me so the jury is still out but
I had a chance to use it on a recent trip to Florida and landed a
couple of decent sized Reds with it. It seemed to cast pretty well,
even in a lot of wind, and didn't spook anything on those gin clear flats.
We'll see how it is with some finicky stripers. Its advertised sink
rate of 1.5 - 2 feet/second makes it a pretty good all around line but I keep
a spool loaded up with Depth Charge 350 for heavier surf, rips, rocks, etc.
I have been fishing with the Depth Charge for two years now and really like it.
It really loads a rod up quick, casts very well and sinks like a rock.
Tight lines.