Re. Plus 38
I have tested it since Oct, on clay court, hard court, carpet; 3 diameters, 2 different racquets.
Main difference is surely the responsiveness, neither Hex nor Hex Plus is close to +38 in that regard. Players who prefer stiffer strings move on, this ones elasticity/responsiveness is just amazing. In that way it really blows away Black Widow, BHB7 etc.
Anybody who appreciates Hex Plus as a step forward from the original string should give it a try. String it up at same tension, have fun. I don't know but guess TW should it offer in a short while.