according to the TRT boards, low SHBG is not a good thing.. a healthy level is needed to effectively metabolize testosterone.
which is why some blood tests are misleading.
you have a guy injecting 1g of test, but his numbers come back at 3000. depending on his SHBG levels, he may have metabolized much of that 1G of test. so his bloods come back lower than expected.
the same reason why TRT guys with low SHBG return bloods of 500-600 on 250mg of test.
I have low shbg and my doc said it was probably hereditary. I take 100mg of test a week and my total test comes back in the 500s but my free test is in the low 20s which is in the upper range. If I remember correctly more frequent injections will help combat low shbg which is why I inject eod.