I ended up getting an older Weller D550 on Ebay. Although costing near the price of a new Weller D550, the older version has the soldering tip held on with nuts, versus the newer version that uses set screws to secure the tip.
I already have resistance soldering units and related hand pieces. Resistance soldering is superior for detail work but the set up is more complicated. I needed something for smaller / quicker jobs.