I have never owned or used a Sirio WD140 but do own a couple of Sirio 6 element 140-160MHz Yagi's and a couple of their very broad band fat ground planes. The versions I have are very well made with anodized 6063-T5 aluminum and rubber O rings sealing critical connections. You can tell there is a lot of good engineering and quality in these antennas. However most of the hardware is not stainless steel and has some type of corrosion resistant plating and I don't have long term history on the rubber O rings and overall weather proofing. I can say the performance and mechanical integrity is very good for the price.
On the DB-2XX dipoles, everyone knows what you get and their metal parts can last 30+ years in some environments and still play fine. There has been some indication later coax phasing harnesses from DB fail prematurely but it seems you are looking at a single dipole and not a stacked system with phasing harness.