I have a gravity feed iron (Sapporo). It's 10 years old and was designed for tailor shops, so it is intended to be turned on in the morning and left on all day long. Like all gravity feed irons for the trade the iron part of it rests on the sole, sitting on top of a heat-proof pad. The tank holds one gallon and the deionizing crystals rest in the bottom of the tank. Depending on the type of water in your area you replace them every year/thereabouts. Other names to look for are Sussman and Naomoto (the cadillac).

I pressed for a drycleaner for a few years and the luxury of generated steam is wonderful. But if you don't have the vacuum table/"buck" I don't really see the point. A quality gravity feed iron will generate PLENTY of steam. As long as you hold your finger down on the steam button and there is water in the tank you will have steam. More than any "home" iron.

(I do a lot of drapery work). Hope this helps.