I have been climbing for a bit more than 2 years now (so make the due discount to my words). I have been mainly wearing tarantulas from la sportiva in 43,5 as a comfortable fit. I also have old scarpa vapours in 44, fitting me nicely (still comfort fit for that type of shoe). I ordered the remoras in US10 as it corresponds to the length of my foot as seen in the chart. I got a tighter fit than what I desired. Should have gone 1 full size up I guess.
The shoes are indeed wide, but my foot is wide on the forefoot, not so much in the back. The shoes were super tight in the front (and the toe box is not roomy, making the fit rather unpleasant), while still having some space in the heel and in the arch. I wanted to try these, but I will now go for a different model as I believe that a bigger size, while solving the discomfort at the front, would make problems worse in the heel/arch area. Another note - these shoes have a lot of rubber in the front making them not very sensitive, but, I guess, very durable.