Just a short comment:
Many thanks to the words by
@Stargazer - I agree with most of your comments and given information.
It is a very good kit with very good quality, and the finished model has a very good appearance. Manuals and drawings seems to be first class.
So I completely agree, that this kit, with so much prefabricated parts (you wrote: "in some ways it assembles much like a plastic model") and documented (manual + plans), is well designed, so that a lot of modelers will produce a good model.
I personally like more the POF models, but this is completely a personal taste. Sometimes we need also the challenges of imperfection or semi-prefabricated parts. with sanding, cutting etc. - and the models will have much more often a different appearance, more individual results.
I am pretty sure, that NO manufacturer (worldwide) will get really rich with their kits and I am also very happy and glad, that there are some enthusiasts out there developing for us new challenges and tasks. And the question if a requested price is high, too high or correct? ..... the market will tell -> every possible customer is deciding by himself, which price he is willing to pay.
The Vanguard model is in the same price range (and size and scale) like the HMS Diana from Jotika, and looks like a really better and / or uptodate kit.
I would also like to see a building log of the Sphinx here in our forum. Would be very interesting to see......
BTW:
There are several drawings available at the NMM, which could be interesting for the modelers working on the model later on....
F.e. this one

Scale: 1:48. Plan showing the body plan, sheer lines and longitudinal half-breadth proposed (and approved) for Sphinx (1775), a 20-gun sixth Rate to be built at Portsmouth Dockyard. The plan includes a table of the mast and yard dimensions. Signed by John Williams [Surveyor of the Navy, 1765-1784]
or this one is highly interesting

Scale: 1:48. Plan showing the outboard expansion and the inboard expansion for Sphinx (1775), a 20-gun Sixth Rate. Signed by John Ancell [Assistant to the Master Shipwright, Plymouth Dockyard, 1801-1814].