Yes Andy,

The fast heat/cool times indeed imply a very low thermal mass. But that isn't my principle concern. It's been a lot of years since I needed to solder a 1/4" land pad. And given that the tips seem to need that rather large dielectric separating the two halves I don't think they're going to be producing any fine pitch needle tips. (Yes, I saw their conic tip, but it's a far cry from small enough to do fine pitch.)