David, I reckon even if the pictures had been made on film to begin with, they still would have ended up as digital prints. Certainly with architectural work, shooting large format for the movements and then scanning for precise colour control seems to be a no brainer. The most sensible option is using large format cameras with digital backs. On a practical level, optical prints for this type of work wouldn't make sense. Can't imagine you'd find many purist architectural photographers seeing as it's a commissioned job, rather than a fine art. When he insisted the capture "must be digital" I suspect it's less to do with 'accuracy', but control of colour. This type of work depends upon precison, not painterly subtle hues.