HELL FUCKING YEAH!!!
This is a great thread Ulter!!! If you are serious about gaining size, bigger doses will always yield larger muscles. Anybody that has tried them know this. No ifs, ands, or butts about it! The only culprit I see with larger doses is that some are prone to gyno....BUT, this does not mean that the larger doses did not give more gains. If you are sensitive to gyno, then there are routes (anti-e's and inhibitors, etc...).
That being said, some may be able to get away with lower doses for "cosmetic" improvements, but if you are serious about gaining size for competing, then larger doses are a must unless you have phenomenal genetics.
About the amount of receptors....
From what I have read, and cockdezl has mentioned this in the past when he was here (not sure if he posted a study), but to saturate the AR receptors, the dosage seems to be fairly high....if I remember correctly, it is thought to be at around 2 grams per week (correct me if I am wrong though). That also being said, I don't advocate over 1 gram per week of test unless you want to really get serious about competing.
However, it is ridiculous to believe that 300 mg's Vs. 600mg's is even of question. At that dosage, sides are minimal between both, while the gains are dramatically more for the higher dosage.
BMJ