that this claim, (about the RM009), is a bit silly, but for some reason I haven't seen it disputed yet.
As I'm sure anyone who thinks about it will realize, there have been any number of mechanical watches that weigh less than 28 grams, (head only). Consider how many tiny women's watches have been made over the years, for instance, that might weigh a fraction of that.
It doesn't need to be a diminutive women's watch to come in under that weight, though. The first watch I selected from my collection to place on the gram-scale this morning, a vintage Junghans Max Bill Chronometer, weighs 26 grams. A vintage Hamilton Intramatic with date weighs about 28 grams with strap and buckle attached. The watch head alone is only 22. Since this is an automatic with rotor, I'm sure you can appreciate there will be many, many men's HW watches that will come in well under even that weight.
Please understand that I very much admire RM watches for the innovative and technically exciting construction techniques they represent. I just think RM doesn't need to clutter up the issue with such silly, hyperbolic claims attached to them.
(And if you're reading this, Mr. Mille, I think I should be gifted an RM watch, maybe an RM005 Ti, for drawing this serious concern to your attention, don't you? Thanks!) >;^)