Hi Tush915,
Tempurpedic is in the group of “major manufacturers” that I would avoid. Most (not all) of their mattresses use mid to good quality/density materials but they are not good value compared to many other smaller manufacturers.
I would certainly consider Verlo as a better value alternative but to make meaningful comparisons you would need to know all the specs of the layers in each mattress. The online description of the Verlo Crescendo is different from what you described and I would want to know the exact layering (not a guess) before I considered it although I do think Verlo in general has better than average value. Some comments about the specs they provided …
4 lb memory foam: This is a medium quality/durability memory foam (used in combinations with other densities of memory foam in the Tempurpedic Cloud mattresses) but is quite popular because it is generally (but not always) softer than higher density memory foam. If you are lighter (say under 200 lbs or so) I would consider it. If you are over 200 lbs and durability is a bigger issue … I would be a little cautious about using 4" of 4 lb memory foam.
You can read more about the many different versions of memory foam in post #9 here but in general I would lean towards memory foams that were a minimum of 4 lbs and higher densities will be more durable with 5 lb memory foams being in the “most durable” range.
Acella-Flex: this is generally a good quality polyfoam and I believe is a 2.1 lb density but I would ask to make sure.
Warranties are mostly meaningless and are more about marketing than quality or provide any indication about how long a mattress may last. You can read more about warranties in post #174 here.
Some of the memory foam manufacturers and retailers that I use as a “value” reference are in post #12 here. If a local mattress that used similar materials and layering was in the range of 20% or so higher than these (depending on each person’s “value equation” which takes into account all the factors in a mattress purchase that may be most important to them) I would consider them to be reasonable to good value.
If I was limited to a choice between the two I would probably go with Verlo but I would want to make sure the specific mattress was suitable for you (because of the medium density memory foam) and for a basic 4" of 4 lb memory foam over 7" of 2.1 lb polyfoam it seems on the high side to me as well.
Phoenix