I too can vouch for the Weller 100. Very reliable and long lasting. We own a stained glass shop and go through hundreds of pounds of solder a year. The Weller 100 is the only thing we use. If you remove the nut periodically and apply some high temp anti seize it will last longer. Replacement nuts are available from Weller. If it ever seizes fast just cut across it with a cutoff disc and replace it. About the only thing that harms these is leaving it plugged in and unused for long periods.
Cooper Tools is a great company too. If it ever fails return it and they will probably send you a new one free.