Well, heck. I was writing a reply when you posted this.

I just went through the process of modifying gainroot the other day and I'd offer that the instructions are pretty vague on the point c_legaspi is asking about.

Having just gone through this whole ordeal recently (successfully, as far as I can tell), I was going to provide an answer that I thought would help clarify the instructions and explain the theory behind which lines to comment out to the extent I understand that theory (which isn't very deeply).

Can you explain your warning any futher or are you just reiterating the warnings provided with the instructions? I'd be honestly surprised if anyone read the already existing warnings and thought that these modifications presented no risk.