Interesting question, something that I have deliberated over before myself.
I think the success that you will have with these products, particular the big three are largely governed by way of your attitude towards them and hair loss in general.
If you doubt the efficiency or success that you will have by way of influence from your own thoughts and what you read (perceive) then your chances will be greatly diminished.
It seems that many people on these forums have little success, not all, but an increasing amount do not. Perhaps this forum, whilst beneficial in some respects, affects results in others.
How?
If you are someone who tends to read every sub-topic on this forum you will get a cross section of posts that are positive, optimistic, neutral in tone, negative, pessimistic and down right worrying.
Some of which are taken at face value or with a grain of salt but others of which are taken seriously, literally and absorbed in your subconscious belief system.
I have little doubt that this emphasizes the rate of success or failure. Sometimes there is too much information for our own good.
An example would be a friend, who by all means was extremely diffuse, horribly is probably a better word to describe it, however after embarking upon the use of Propecia and Propecia alone he has regrown the majority of his hair bar his hair line which you can still notice obvious thinning and recession.
This is someone who has not and does not use forums of this nature, but rather pops a pill, once every now and then (literally) and gets on with his life, successfully in a socially rich environment with friends, a loving girlfriend and successful business; results abound.
This is not scientific proof by any means but it certainly adds food for thought concerning my view on this topic. I wonder how many more cases like this exist.
If this is not making much sense to you, I'll further elaborate by saying the purpose of this post is relative to previous (brief) posts that I have made which talk about how thoughts (perception of environment, internal and external) influence your cellular biology.
Reading this forum is but one path of influence that for better or for worse can determine the return on your investment concerning your hair.