Hesson's research aligns with my own experience. So far the Technics headshell is the lightest I've come across. But spend the
$15.95 and replace the leads with HPOFC ones.
The medium compliance version of the Voice has a compliance of 22, which is on the high side of medium. It weighs 6.8g. The effective mass of the stock SME 3012 R tonearm is 14g with its standard headshell, so total effective mass is about 21g. This cart-arm match creates a 7 to 8 Hz resonance which is at the low end of the ideal zone. If the Technics shell can reduce the effective mass by a couple of grams, it'll put the resonant peak solidly in 8 Hz territory, which is closer to ideal.
No other headshell is lighter than the Technics, though there are a couple of wooden Yamamoto headshells (boxwood perhaps?) that come in at 8 g which should be close enough.