If it's labeled as "T-Series" or "STX," then it's VERY good stuff - basically, the exact same thing as the old Black Talon rounds, just minus the black Lubalox coating on the bullets. However, if it's simply labeled as "JHP," then it's basically the same exact thing as Winchester White Box JHP's ... which are also the same thing as Silvertips and SXZ JHP's, all the exact same bullet design, just with or without the silver or black coloring on the bullets.
The Winchester White Box/Silvertip/SXZ/Ranger JHP's, as far as being defensive ammo are ... well, not bad at all, really. Nothing outstanding, but not terrible. It's just old technology from the 1980's or early 90's. It's not like it's going to just bounce off of a bad guy and have no effect simply because newer, fancier, more effective ammo has since been invented and marketed. It's just not the best load available, that's all. I'd feel fine carrying it for defense if nothing else was available, but eventually I would look for something a little better and then use that stuff for practice ammo.
Also, the "subsonic" designation is simply because it's the heavier 180-grain bullet, which is naturally a slower-moving load than the 165- or 155-grain loads. Doesn't really have anything to do with the powder loading, per se. No matter what, ALL of those .40 S&W loads are just wimpy, watered-down versions of 10mm anyways, sooooo...
FWIW, our issued duty ammo at my job are the 180gr Ranger T-Series rounds in .40 S&W. Good stuff.