I bought an RT-58 about 4 months ago as a 1st road bike. Can confirm its a great machine. Light in comparison to most at this price range, Tiagra all works well still and very comfortable on 60mile+ rides. Cant fault it. I went for a large and am just over 6ft. Seems to fit me fine.
Obviously not had any other road bikes to compare directly but with a full carbon fork, tapered headset etc it does stack up very well on spec. Planet X were great with their customer service also contrary to some reviews! Updates sent all the way through the process as well which was nice.