I suppose you could consider lugged 853 rare because it has been really popular as a production steel material, and they never use lugs. Pointing out that A2 air hardens in properly controlled oven environment really doesn't mean anything wrt to a welded frame. Seems to me that the material away from the HAZ is going to be just as annealed as the tubing near the lugs. So the material condition will be a band of hardened steel, a band of annealed steel, and the bulk of the tube in the as-shipped condition. The ******** generators are really going to have to wind up to full form in order to convince me that's superior to a lugged frame.