Hi gtr89,
Most of the mattresses you see will be either tight tops, pillowtops, or eurotops.
Tight tops have all the foam and components in a single cover.
Eurotops have the top layers in a separate enclosed compartment that has the regular mattress ticking material on top and usually a non woven fabric in the bottom of the compartment between the eurotop layer and the bottom layers or components of the mattress. They are secured to the mattress to be “flush” on the sides. In the case of the Ultimate Dreams Eurotop this compartment has a zipper.
Pillowtops are similar to a Eurotop but they are like a separate topper where the join between the pillowtop and the rest of the mattress is recessed so the edges of the pillowtop can move more freely which results in a slight increase in softness.
While “words” like pillowtop and eurotop have come to mean “softer” … it really isn’t the case because any thpe of construction can use any layers of foam and you could add thicker layers of foam in a tight top that a eurotop or vice versa so they are really more about the way the upper layers of the mattress are attached to the lower layers.
There is a discussion of the potential benefits of a thicker base layer in post #14 here. A post about the specific benefits of the Ultimate Dreams Eurotop is in post #2 here along with post #39 here.
As you can see … for most people there wouldn’t be a difference they could feel unless they were much heavier than average (say mid 200’s and up) and Dreamfoam has said that for most people the feel of the two mattresses is the same.
The real advantage of the Eurotop is the ability to exchange a layer, split the top layer (a different firmness level on each side of the mattress), and as you mentioned to be able to replace it down the road with a different layer if it wears out faster than the deeper layers of the mattress (the upper layers are the most prone to softening even though latex is the most durable of the different types of foam) and also if your needs change down the road you can also change the comfort layer without replacing the whole mattress.
The 1.5" quilting layer is already very soft and thin so further softening of this layer won’t really affect the feel of the mattress. It is just there to soften the hand feel and surface resilience of the latex. If it was thicker it could be a “weak link” but thinner quilting layers are not really a durability issue unless there is more lower quality foam underneath them.
In some ways all of these mattresses could be considered “higher end” (by the standards of many manufacturers) but the Eurtop has some benefits that the others don’t have.
Whether these benefits are “worth” $300 would really depend on the preferences of each individual, their “risk tolerance” and their “value equation” (what is more or less important to them). It would probably be fair to say that for some it would be while for others it wouldn’t.
Hope this helps
Phoenix