I've scanned through many but not all of the comments in this interesting thread. As chair of the PDGA Tech Standards Committee since 1988 I've seen all of the targets submitted for testing/approval/certification over that span. Consequently, I have a unique perspective on many of the issues discussed here.
As many have noted, a certain level of variability is permitted in approved targets, with some finding that to be a good thing (or at least not such a bad thing) and others not. I think it is important to debate whether absolute uniformity should be a requirement or not for approval. This is true both in general as well as for different PDGA tiers, and for outside tours such as the DGPT. Believe me, the TSC spends countless hours debating issues like this, often reaching a consensus but in some cases not. In the end we opted for a middle ground in the target standards, whereby there is some flexibility in design parameters so as to encourage/allow possible innovations/tweaks. And there are more rigorous requirements for the Championship level. Of course, our philosophy on this approach could be change in the future but there would need to be a compelling need to do so.
As the TSC Chair it is not my role to endorse particular targets, and I am not doing so here. But I think there are some targets not on the DGPT approval list that are equally as effective if not more so than the four they list. Those targets are commonly made by smaller companies, sometimes ones outside the US, that touring pros are less likely to have been exposed to. I'm sure the touring pros have done a good job of picking the best ones they know of, but that excludes others that are exceptional. It's not surprising/coincidental that the four selected are made by companies who sponsored many of the touring pro who voted. I'm not saying that's a bad thing, just an interesting observation.
It is noteworthy that many who play in the 27-hole Lemmon Drop B-tier near Tucson, which is played with 27 different Championship targets, find the variability in the targets is one of the appealing aspects of the tournament. For your viewing pleasure, attached are photos that show a number of the approved targets in my backyard.
Thanks for your perspective, feel free to post more.
Also, amazing basket collection, I'd like to stop by and steal one lol.