I believe androgens decrease my recovery time. I also share your concern about certain compounds strengthening collagen. I was using BPC-157, GHRH/GHRP, TB-500, and others. I believe I started getting stronger rather than longer. I was having trouble reaching fatigue hanging with 14 lbs after only two months.
To combat the toughening, I incorporated a number of other compounds in an attempt to influence collagen remodeling. Here’s a recent post on the topic: Taking the Chemical PE Plunge
I also have a relaxin analogue being custom synthesized. It will either be the holy grail of PE, a complete waste of money, or something in between.
As for androgens, I’m currently on test p, mast p, methyltrienolone, proviron, and DHT. I don’t think they’ll have a big impact on growth, but it will be an interesting experiment nonetheless.