I was able to play a little more last night with both stringjobs. I've got about 4 hours on the Silverstring racquet and have decided that it's not the one for me. It's gotten a little too springy and the mains are not snapping back anymore.
On the other hand, I am really enjoying the Iontec Salmon in my other 99S. It's got about 3 hours on it and still feels great. Feel on impact is still solid and the mains are snapping back fine. It feels way better than the Silverstring when blocking back hard shots at the net. Groundstrokes wise, they are about even, with Silverstring having a little bit more pocketing and the Iontec having less of a trampoline feel. There is only some light notching. Looks like it will last a good while longer. Maybe 7-8 hours total.
I've got a set of Iontec Hexa 1.25 that will replace the Silverstring. If it plays exactly like the regular Iontec salmon but with a liitle more grab, I think I've found the string for me. At $70 a reel(about $4 a set), I would be very happy