not sure you’ve been doing decent research then, the Rossini and Vivaldi have been reviewed at length on every mag and the network box is now getting a bunch of reviews
https://www.dcsltd.co.uk/products/vivaldi-dac/reviews
https://www.dcsltd.co.uk/products/rossini-player/reviews
https://www.dcsltd.co.uk/products/network-bridge/reviews
I would argue that in fact DCS is more reviewed than the others you mention
DCS do however try to manage the second hand market in a Ferrari like manner and hence you find factory approved used items from them which come with after sales service and software upgrades as opposed to the private sale non supported ones, obviously the latter are cheaper but the buyer has the choice of which way to go
As to the reviewers they all have biases which are not hard to spot once you spend time reading and listening. With so many on line opinions it’s not too hard these days to find someone who’s ears you trust
Ps the Puccini was also reviewed by both the main mags as well
https://www.dcsltd.co.uk/products/puccini-player/reviews