I have a DCS 3000 (I think) return pump. Has been working just fine for the past year or so.
I don't think there's anything wrong with these pumps if you know what you're getting into. They're obviously not Ecotech products and don't have the reliability or customer service. They probably won't last as long and they probably aren't as polished. But, you pay only a fraction of the Ecotech price. A Jebao 12000 return pump (capacity of about 3,200GPH) is $98 on Ebay. The Vectra L1 (capacity of about 3,100GPH) is $450. To me, I'd rather take the gamble and buy a Jebao and maybe have to buy a second if the first breaks. If the first one fails and I buy another, I'm still ahead. If the second and third also fail and I have to buy a fourth, I've still spent less than I would have paid for a Vectra (4*98 vs $450). I think it would be highly unlikely to have 4 of these pumps fail on me, so I have no problems buying and maybe having to replace it later.
Not everyone shares this view, and that's fine. This is just my opinion.