After going through the posts on the forthcoming changes and the collective wisdom of forum posters, I conclude that:
1) as a PC member on monthly rollover using PayPal, I may get temporary disruption in service, so I may actually by default, fall out of PC membership until the payment deduction for the new store platform is working smoothly.
2) as a Poser user, I can't hope to get much more relevant content from this source. But, I still use Bryce and Hexagon, so it may still be worthwhile to peek into the website from time to time.
3) On the actual occasions in the future, that I might want to buy something Bryce or Hexagon-related in the new store, I either spend the voucher on proprietary content, or pay the full whack to third-party vendors (assuming that such vendors choose to continue selling at this store, and not sell elsewhere).
4) I don't have issues with the zip format, provided the compression used is friendly to most unarchivers / decompressors. For example, there is a certain level of high compression under StuffIt, which cannot be decompressed except by using StuffIt). I note that my old cdrom archives of Daz 3D EXEs cannot install using my windows 7 32-bit system. I can install those old EXEs using a windows 98 32-bit system. Whoa.