Nice metal work Mick.
Although I am also suspicious about the whole "Sumbawa" hype, I can imagine you being tempted by this level of workmanship.
As for the Sumbawa Hype, I am far from an expert, but I do visit markets and fairs on a regular basis for the last 15 years or so. but 10 years ago I never saw any keris being named "Sumbawa".
Nor did I see the style with fancy toli toli's, stones etc.
For the last few years they appear on the market, and suprisingly always sold by collectors / traders that visit Indonesia on a regular basis (ie. visiting once or twice a year).
Traders that get their stuff from estate sales and from elderly people cleaning up the house, never come up with Sumbawa material.
Although sometimes well made, Sumbawa keris' will not end up on my wall
very soon.