The Pace ADS200 is essentially a ST/WJS station combined. It's newer technology and uses two new series of cartridge tips on the TD200 handpiece, 1130 standard and 1131 ultra tips. The station also runs the MT200 mini tweezers. Pace plans on releasing the 3 channel MBT450 which should have built in vacuum for desoldering.
The only reason you would run the ST is if you wanted to run some of their older handpieces. The WJS was high power but only ran the one soldering handpiece.
So Pace ADS200 w/TD200 is the way to go, get the ISB (instant setback) version, plus a few different carts.