Delta, while not exactly a huge player in the home consumer/computer enthusiast market, is one of, if not the largest, power supply makers in the server/IT/OEM arenas. (I've seen it mentioned in articles in DigiTimes that Delta accounts for about a 50% market share of the high end server and workstation power supply market.....a major player indeed!)
Delta has been around for a long time....founded in 1971. And again, while not a retail/consumer oriented company, it has received award after award from those it does serve, the OEMs, etc., that Delta does serve, including HP, Fujitsu, Dell, Intel, Microsoft, Siemens, NEC, Eaton, Rockwell, Nortel, Cisco, IBM, Samsung....and a host of others.
So I'd not fret about Antec moving from Seasonic to Delta as their OEM supplier for their Earchwatts power supplies....if anything, they should be made at least as well, if not better. This is, of course, if Antec allows Delta to build to their usual quality and doesn't make too many penny pinching decisions in the power supply componentry choices.