According to the FCA report two years on from the new rules taking effect there has been a reduction in product bias, with a "very noticeable decline" in sales of products that previously came with higher commission.
There was an increase in the sale of products which paid lower or no commission pre-RDR - a sign, officials said, that commission is no longer a driving factor in advisers' recommendations.
The study also showed an increasing number of financial advisers gaining further qualifications, demonstrating growing professionalism in the sector.
However, the regulator reported that while product and platform costs have broadly fallen, adviser charges appear not to have decreased.
It stated there was "little evidence" that the availability of advice has reduced significantly, with advisers still willing and able to take on more clients.
Europe Economics, which carried out the work, found that while a small group of those with less to invest may find it more difficult to find an adviser, there were still those in the market willing to serve them.
Martin Wheatley, chief executive of the FCA, said: "The RDR aimed to create a truly professional financial advice sector; one that provides advice based solely on investors' best interests. It is still early days but the indications are that the sector has responded positively to the reforms.
"Importantly, we have seen a reduction in product bias, with a very noticeable decline in the sales of those products that before RDR came with higher commission.
"These are positive signs but we know there is more to do. For example, early next year we'll be looking at how we might encourage better disclosure of information to consumers. And, in 2017 we'll undertake a further review of how the RDR has worked. It is vital that we continue to keep these wide-ranging reforms under review."  
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