Reviews are a powerful capability that gives credibility for transparency. You also have to be prepared for those open conversations - as you know from referencing those three sites. This means committing to authenticity (as cooked reviews are a major mistake some have attempted) and navigating the appropriate moderation of reviews.
It really is driven by what your B2B goals are on your business site. Some sites have handled building credibility through questions and answers (i.e. Quora, LinkedIn, et al). There you can allow users to rate answers - and also allow for flagging of those that don't pass the genuine test.
I call it the Amazon effect (others use eBay) as they were among the first to offer reviews on a massive scale. It is powerful and influences decision making, purchasing and attitude toward products, services or even the site itself.
Having designed policies for social communications, customer service communications and more in B2B environments - I've seen reviews work well and not so well. It can be done - but requires judicious planning for rules of moderation and engagement, and for how readers of reviews can reward or flag them.
I'd be glad to hold a follow up on this and talk through those elements.
I believe that reviews, especially "verified" ones that can only be left by customers or other association (ex: investor / vendor / etc) are critical to help get someone over the hurdle of making a request.
Think about making the decision to rent a movie, what do you want to see to ensure you're not making a bad decision?
This is especially true for less concrete service like general contractors, etc - since there's no fixed unit of the transaction you can curate for (ex: Uber drivers, Airbnb listings).
Always up for a call if need be.
Customers Reviews are a great way to build credibility and increase trust in your customer’s mind. A recent survey (Local Consumer Review Survey 2013) by BrightLocal.com revealed valuable information about how important reviews are and how they influence the consumer’s trust and decision to contact local businesses. The number of consumers who read online customer reviews to determine whether a local business is a good business is increasing every year. Here is the link to BrightLocal report
In addition having a frequently updated page with reviews on your website is a great on-page optimization strategy and an online reputation management method that is often overlooked.
"YES" - current, high-profile (known business representatives) reviews establish realtime credibility.
"NO" - outdated, abstract reviews can appear desperate.
Personally, I stay away from self-promoting reviews in my marketing. New clients can see portfolio examples of my work from clients past and present .
The quality and craftsmanship of your product or service far outweighs any referral.