I was told this also (by a C&J vendor in the U.K.) but after researching various threads here regarding the fit of the Tetbury I decided to size down one full size instead of half a size. That was the right decision for me as my Tetbury's couldn't fit any better. Search for those threads.
I've searched around and when you search hard enough, they kind of contradict each other. I sized down .5 for my first last 337 shoes and had to return them. I based my initial decision with what I found on the forums in addition to asking a couple of stockists. With insurance and such, shipping came out to be around $40-45...ouch.
What size are you in other makes? Perhaps that will help me gauge more accurately. Thanks for your 2 cents BTW!