Never used Ribble nor Chain Reaction, but last month I did place my first order with Merlin Cycles. The price for a Shimano WH-RX31 wheelset was utterly unbelievable. So fantastic that I paid for the expedited, tracked shipping. It arrived so fast, from Ireland to the West Coast that I could hardly believe it. Only 'gotcha' is that they use DHL, and someone has to sign for a delivery, (I wasn't going to have them leave a wheelset on the front porch all day). Since I am by myself and work during the day to pay the mortgage, I had to reschedule for the following Friday when I would be home.
Other than DHL, I was pretty happy with the transaction, so, about a week later, I placed an order for a 6800 cassette. This time I did not pay for the expedited, tracked shipping . . . and I am still awaiting delivery. The stated delivery window closes at the end of this week, and I'm not sure what to do if it doesn't arrive, since there is no tracking, I have no idea where in the pipeline the cassette is.
In the future, I'll continue to use Merlin as the need arises, but will pay the extra for tracked shipping. Having a really difficult time right now not jumping on an Ultegra WH-6800 wheelset. $302! Come on! That's a Ben Franklin less that the cheapest price I every paid on eBay for an Ultegra wheelset, (good wheels, by-the-way). They have Dura-Ace C24 wheels for a steal of a deal too! The retailing system in the U.S. is broken. No wonder shops are closing.