To comment on your concerns: "But wondering about major systems: slides, suspension, axles, appliances, structure."
The slide mechanisms, suspension systems, axles, appliances are all "industry standard and likely to be found on trailers from all of the major manufacturers.
The structure is essentially competitively built and very (extremely) similar across the RV manufacturing industry.
What differs, IMHO, is the "eagerness" of the manufacturer to step up to the plate and, as "glittery" as it may seem, the décor.
You'll find (I think) about a $5-10K range difference for comparable models produced by all the competing manufacturers. What you get for that money is improved customer support and "eagerness vs reluctance" to work with you to solve problems. If you have problems and need them to step up, you're ahead. If you don't have problems, then paying the extra for better customer support cost you something you didn't need or use.
All the manufacturers have a "legal obligation to meet their warranty obligations" The difference is whether they "jump at the chance to keep you happy" or "you have to drag them through broken glass to get them to even accept responsibility for a problem"....
Of course, this is just my opinion of the industry as a "conglomerate of different manufacturers" and there are some different experiences among owners. Some have never had a problem, some had minor problems and the manufacturer stepped up and fixed them, no questions asked while others have had significant problems and fought "tooth and nail" to get their trailer repaired. As far as I can tell, there is no rhyme or reason to who gets what and which manufacturer will be "nominated for the Golden Award" this year....
I know this doesn't give you any specific info about the trailer you're interested in buying, but honestly, it's very difficult to compare any floorplan or brand to another unless you've owned both and things one owner finds wonderful can easily be the reason another owner would NEVER buy that damn thing again. So about the best you can hope for is that your purchase experience is similar to someone else's purchase experience and that you get to talk to the same CS representative that helped them if you need to call the factory.... Otherwise, it seems every trailer has its own personality and its own problems, unique from all the others.....
2015 F250 6.7l 4x4
2014 Cougar X Lite 27RKS