Weight, I think there are a lot of variables that are hard to control, and that makes it difficult to really know what's causing any improvement. Some AAS promote water retention while others don't, and some seem to work better for a particular person than others.
Another factor is; are the dosages exactly the same, right down to the ester. As I'm sure you know, the actual amount of Test your body receives when using Test Susp. is quite different than the amount of Test your body receives when using Test Cyp. There's also the benefit that comes from simply thinking something will work better and therefore it does. It's hard to keep all variable exactly the same, including; life style, AAS dosages, training, eating and rest for 20 straight weeks.
Speaking personally, with about 24 years experience using AAS, when I get really strict with all variables, I can almost always identify changes in training and eating as the prime reasons for any unusual physique changes when on a cycle. What I mean by this is I know how my body reacts with various AAS, various combinations and various dosages. When I make an AAS change, I generally get the expected result within the limits of what the AAS can do. Any changes outside those limits, can usually be traced back to training, eating or life style issues.
Take for example, a sudden physique improvement or sudden weight gain half way through a cycle, and it's clearly due to a change in type of AAS. That change however, can only be as great as what will happen within the confines of the type of change expected with that particular AAS and dosage. Adding Adrol at 75mg/day for the last 6 weeks of a bulking cycle will cause a jump in my weight. But that's only due to Adrol's characteristics, not due to different AR sites or refreshing the AR sites or anything else.
As far as the AR sites and the drugs that interact with them, again, there is one type of AR site and all drugs attach in a similar way. Some bind more strongly with the AR than others but they all use the same AR sites.
MaxRep