We have been on many small group holidays and offered reviews for subsequent users. However a recent and very unsatisfactory trip with Intrepid to Peru I found they only publish favourable reviews on their website rendering review information worthless. So beware! Other companies eg Exodus show all reviews regardless.
The group was only 6 and I think Intrepid used an untried inexperienced and incompetent tour leader. They acknowledged their shortcoming, but my real gripe is that they only publish favourable reviews so I cannot trust them anymore. I'll stick with Exodus!