I guess the decision needs to be weighed along several lines.
As of today, there are 10,877 of the various models of Vans RV aircraft that have been built and are flying! That is quite the testament to the design and its popularity. Let me look: how man of the Cougars are flying? Oh, yeah: none yet. OK: that would influence my decision.
Pulled rivets as opposed to driven: are they faster? Yeah, maybe. Are they flush or round head? If they are round head it will look like a factory-built. Look at a Cessna wing (or fuselage) and compare that to an RV. Smoooooooth. If they are flush, every one of those holes still needs to be drilled, deburred, countersunk and a rivet pulled. Same with a driven rivet and MAY take a little longer but once you get good at driving rivets it will be a new talent you are good at and can be proud of! And most rivets can be driven without help. And once you get good at it, they go quickly. Driving rivets is not what takes time in a build...... I don't want to say ANYone can pull rivets but, I mean, they make furniture with pulled rivets.
Have a question on a construction problem you having trouble with? Call the factory. Well, you can do that with an RV....they will chat with you....but this forum is a gold mine of information. And there is likely someone close to you who is in the process of building an RV-something. And most builders will be way more than happy to show you around their project. Letsee: Cougar. Maybe not....
OK: How does the Cougar fly? What are it's flying characteristics? I suppose you could extrapolate from the Panther but the RV-3 and the RV-4 fly differently. I would venture to say (ask anyone on this forum) that the RV series.......any one of them.....may be the best flying aircraft in the air. Go 200+ kts and stall at 45-50: does the Cougar do that? Does it fly....as an aviation writer once reported...as close to the characteristics of an F4U Corsair as anything else on the civilian market? Why do so many ex-military pilots fly RVs? Hmmmmmm.
I think those are just a few of the things you need to consider. When I was trying to decide, there were not that many choices and information on building was through the factory or local builders. I cannot tell you how happy I am....for SO many different reasons.....I chose the RV-4. Would I do it again? Oh, yeah! But I'm into flying the one I have...... And back when
I was a kid, there was just no such thing as matched-hole drilling. It was done from a pile of formed aluminum and a big roll of plans.....back when
I was a kid....and it did eventually get built.....
I suppose you could have guessed, asking on this forum, what would be the answers you would get. Are we biased? OH, yeah: but for a multitude of reasons. Most people who build an RV do not give them up.....unless they are about to or in the process of building another one....!
IMHO........