I hear you Hunting Dog and I sort of agree with your upgrade what you can philosophy. Except sandwhich floors are sort of structurally compromised from the start. The foam will not remain ridged for the lifetime of the RV. It is inevitable that soft spots will develop in high traffic areas.
In some cases there is not a lot you can do in certain scenarios to repair this issue.
Sandwich floors are very common but they are really something to avoid.
In order to avoid the sandwhich floors you have to migrate to a more expensive unit. To complicate it even more, sandwhich floor are inherently structurally compromised. The floors become even more a liabilty when they are not supported properly or compromised by a duct are wiring chase.
Many are not aware that the sandwich floors are a liabilty, they don't understand why its important to have t&g sub flooring on their must have list.
To their credit sandwich floors are lightweight and provide insulation, but if the floors are not sturdy they quickly become a liabilty.
Beefing up the sandwich floors can be a simple task or it can be very involved.
Avoiding the floors from the start is the best solution. Convincing manufactures not to use sandwich floors is a better solution. But Huntingdog is probably right. SAndwhich floor are heere to stay for the foreseeable future