I turned 50 this year, I teach, coach local high school teams, and also string a bit. I've stayed away from the poly realm for a while because I'd prefer to not put my arm at risk for serious irritation or injury. Never had TE or that sort of injury, but I've seen it happen among local players, both younger and older, after getting into that string type.
I stock reels of Isospeed Baseline in several gauges to keep handy when anybody needs a basic hybrid or full poly setup and it's been rather well received. The most popular gauge among my "clients" has been their 1.20mm as a main in a hybrid with a 16 ga. syn. gut and I decided to do some comparisons with these strings so that I'd have an idea of the different features that come with the different gauges.
After sampling the 1.20mm Baseline in a hybrid in my Volkl C10 - a soft, hefty, and supremely arm-friendly racquet - I was surprised to find that this layout felt no more firm than a rather tight bed of 16 ga. syn. gut. Even compared side by side against other poly hybrids including "softer" poly options in thicker gauges, this light gauge of Isospeed proved to be the softer choice. While that's all nice on it's own, I also found a nice boost in consistency, control, spin, etc. from my Volkl with the poly hybrid compared to a full bed of syn. gut.
I don't use a poly hybrid in all my different racquets these days, but both of the C10's I keep in my bag now have this "skinny hybrid" installed and I've been fine with them for a couple of months. I've seen this hybrid also work well for a couple of local players who have worked through an irritation or injury in their past. In general I believe that there's more inherent softness to be found in a thinner poly option. Even if it loses tension a little more quickly or tends to snap more quickly than thicker alternatives, that's where I'd go first if I were you.
