We just swapped out the demo for a 200 Ohm version, so far it seems improved.. not the other way around! Much more air up top and defined, while still maintaining the natural mids and bass response - this is without burn in which is interesting! Have had quite a few people prefer it already, even from someone who tried the 100 Ohm prior, much preferring the 200 version!
DAC can be optionally installed down the track, so perhaps they just had the 430HA in stock and are adding the DAC for you, same thing - it would actually cost them more that way but I think you may get it quicker if they didn't have the HAD already.
Honestly haven't seen any issues with the build on the HE-1000, have played with quite a few units myself and gone through a lot but no returns as of yet, if you have had multiple issues it is very strange!
Violectric V281 for now.. but it's a Moon 600i in the future; had the V281 already so at least a reasonable stop-gap! Have tried the Bryston 4BSST2 which was very good too however, but the 600i Is still the way I will go methinks :)