That's a big question. You can run higher boost at higher revs with more safety than high boost at lower revs.
I understand that the power issue of the bottom end is the main caps. I've never heard of a problem with the rods. My engine has stock rods and Ross pistons, no aftermarket main caps.
I have a Postive Displacement Roe supercharger with 10# boost. With water/**** (recent addittion) I could run 12# boost, but I have a 100hp (usually makes 150rwhp) that I may get around to using one day so I won't change pulleys to upgrade boost. My car with 800rwtq at 2,000rpm and 720hp has tons more torque and hp than what's needed for daily driving so the Nitrous is a "turn on/turn off" modification which is perfect because I wouldn't want any more power for highway or daily driving. I've already got too much power for street tires so I can't give it full throttle unless I have lots of room for fishtailing at any speed under 70mph.
Ted