The only place, where I found anything was the Japanese Seiko website, and courtesy of Google translate the only section that differed was that on lume - and even there I was not sure if it was meant as a comparison to the SBDB005 or to other watches. However if I understood correctly, both were advertised at the same price?
For having had looked into the matter. Have you had the opportunity to see / handle either of the two first hand? JDM watches being a bit of a leap of faith for those of us not traveling there on a regular basis... (fit & feel wise, not quality wise)
But size wise not sure. The largest watch I ever had is a Timewalker, which I believe is 45mm, otherwise all between 37 and 42mm. Probably need to try something of the size but I guess comparisons are always difficult...