Go With On-Site TrueFit Construction,
not Pre-Fab shop welds!
#1 Truer plumb and level fit on site. On-site assembly, not pre-fab, provides the best results specifically suited to the site. This way, the posts and deck can be installed properly at right angles, and be level, even if there are variances in the concrete post locations.
#2 Better transportation and staging on the job site. Less costly and less likely to be damaged than large pre-fab sections, especially for concealed damages or joint stress exposure.
#3 Easier to service and make any modifications in the future.