There is some concern with TRT impacting fertility. Basically, it isn’t a sure enough thing to rely on as birth control. As a little anecdotal evidence, I was watching the documentary Generation Iron with the current Mr Olympia contestants and some of them had young children. And we know they’re on more than 200 mg of test. But if having kids was a major concern of mine, I would be hesitant to commit to TRT unless I really needed it. I just had my first kid and don’t want anymore so it can only help me. You can, like you said, always come off and use hCG to get things going again. Alternatively, you could try hCG mono therapy. I didn’t feel any benefit from it but Chris from Good Looking Loser said he loves the way hCG makes him feel. Everyone’s different.
For the off-season athlete there is no anabolic steroid more important or beneficial than testosterone. High levels of testosterone will promote significant increases in lean muscle mass and strength. This is assuming that the individual is consuming adequate calories. Compounds like Testosterone Propionate are not magical, you will still need to feed your body enough calories. During an off-season period of growth, this means total caloric intake will need to be slightly above maintenance. This will, unfortunately, promote body fat gain. However, the key to a successful off-season is gaining lean tissue while minimizing body fat gain to the fullest extent possible. By supplementing with Testosterone Propionate you will be able to achieve this more efficiently. High testosterone levels will promote a stronger metabolic rate. This is not a license to eat like there’s no end in sight, but you should be able to make better use of your calories.