Mate - no one is going to be able to answer this question - they're only going to be able to give their opinions.
The only way to get a conclusive answer would be for DS Labs to conduct a properly controlled clinical study, or if they already have, provide us with the results.
A lot of the ingredients in Revita have been shown to have some effect (usually in vitro) on hair growth, however, I have no idea as to how they interact with each other, the extent to which they will be absorbed / how effective they will be in a shampoo and generally whether they will cause regrowth. Ketaconazole we know has some benefits at 2% in shampoo, however, whether such benefits will be obtained when Ketaconazole is mixed with the other ingredients in Revita is less clear.
All I can say conclusively is that using the shampoo is probably better than using regular shampoo but I wouldn't set your hopes too high.
I plan to use Revita at some point down the track.
Def