Hi Sam! Sorry for the late reply - I didn't see this entry until just now!
I wear a 39 in most IM - the Beketts and Manlys. Like you I went down a size in the Dickers and bought a 38 (mostly cause that's all they had). I ordered the Jacobs in 39 and they are a bit large. If I wear bare feet they are too big and I feel unstable. If I put on thick socks then they are perfect! I'd rather have a boot run slightly large than be too tight, so I stuck with the 39 (plus my left foot is bigger than my right!). Hope this helps!!
I agree that we shouldn't have to do any 'extras' to these shoes considering the price. That said, I had rubber soles put on mine so I'd feel more secure. I felt like I might slip otherwise - plus, since the soles are made of leather they will run down much faster. I plan to use my Dickers a lot and want to give them a long life!