Couple comments.
1) The image of ER2B on a scale suggest that different hosels weight the same. It seems unlikely that a "Long Plumber" will weigh the same as a "short slant", for example..
2)The image of the website. I cannot find it either at the ".com" link or ".ca". Moreover, if I search "340" or "355" it only shows ER10 weight kit. Perhaps the website change?
3)Those weights listed above are clearly lower than what had become the EVNROLL standard of 355 / 370 / 385. Any thoughts on why?
Personally, I would welcome a 340 gram blade (that I would cut down to 34") with ER technology, but that is just me.