Speaking as the author, yes that page and the linked articles (top left) is up to date and still being expanded, though I can't speak for all the linked external sites (towards the bottom of the page) obviously.
However most of the detailed articles refer specifically to the Garmin Etrex Legend/Vista and so are only applicable in more general terms to other types especially the more modern ones. In that respect it is slowly falling out of date. There are only a few articles specific to what I call the 'new' Garmin types (which all have a characteristic 'boxy' main menu style), but future additions will obviously concentrate on these.
From looking around at audax mass starts, I would say that the majority of cycling GPS users are using one or other Edge model. Informed opinion on this forum would point to the greatly superior battery runtime of the Etrex types (50 hours has been seen, on a single pair of lithium AAs) and easy replacement of AAs. The Edge by contrast has limited runtime and no replacement possible. However it can run on external power and plenty of people are happy with this solution for longer events.
In terms of accuracy, usability and facilities, there's no real difference either way. Big box, small box, is the choice.