The DPR forum you're in now is perhaps the best place for NEX stuff in general.
dyxium is a big sony forum
Dyxum is the place for A-mount bodies and lenses, but by policy it is not about E-mount.
However, NEX is largely about E-mount being the
best and most universal way to use adapted lenses , and those can be just about any brand, meaning relevant stuff is spread over many sites.
PentaxForums has many lens reviews, and I've posted lots there... using Sony bodies.

The site has many active users and any lens that comes in M42 or K mount is fair game -- not just Pentax.
MFLenses is perhaps even broader, but not as active a community.
There are a multitude of other, lens-brand-specific, sites, For example, FDReview for Canon FD/FDn lenses. I generally don't find as much useful info in these sites because their scope is narrower -- e.g., comparing Canon FD lenses to each other says less than comparing to other brands.