There is risk, but life itself is risk. For a higher life there will be higher risks. You move on a dangerous path. But remember, there is only one error in life, and that is not moving at all; that is, just sitting afraid that if you move something may go wrong. You will not be in danger but no growth will be possible.
I'd choose getting 4~5 more inches to my height. Screw muscles. but if I HAD to choose, i'd probably pick arms.
my back and shoulders are already pretty good from swimming, so i dont really need to worry about that