Hi vici0usx,
Your question may be a little more complex and cover more territory than you realize 
One of the things I have been working on for many months is to compile some good and accurate information about the many types of gel foams (gel memory foam and otherwise) so people have a reasonable way to compare them. It’s unfortunate that most of the information about them is mostly marketing and little of it is fact based but I have been fortunate to have a lengthy conversation with one of the top foam chemists in the country about this foam category and with others that have good experience or knowledge as well. Over time as new information becomes available I will edit the various posts around the forum with updated information and update some of the earlier information about gel foams but this will be a gradual process as more information becomes available because my research is still far from complete and the gel foam category is changing and evolving as new foams and technologies enter the market. The gel foam category (particularly the gel memory foams) have not been around for long enough to really know their “real life” performance or durability over the longer term. The exception is buckling column gel materials (which use a stiffer gel and have columns which “buckle” under pressure) such as intelligel or orthogel (and also see post #7 here) which have been used in consumer mattresses for a little over a decade.
For now though … you will find some technical and safety information about the soft solid elastomeric gels (such as Technogel) in post #4 here. Note that they are not memory foam although they do have some visco-elastic properties.
You can read more about the three main cooling technologies (thermal conductive materials, phase change materials, and ventilation/humidity control) in post #9 here and at the end of post #4 here.
Finally you can read a brief description of the different types of gel foams more commonly available (and this will be updated as newer types of gel memory foam and more detailed information about each type becomes available) in post #2 here and an overview about gel materials in post #8 here.
Gel materials themselves (soft solid materials) in other industries have existed for a long time but their use in mattresses only goes back in the range or about 5 years or so and the gel memory foams and the gel category itself was made much more popular when Serta introduced the iComfort in early 2011 and became a big marketing success which was copied by most other manufacturers. It also led to sales that helped propel Serta past Sealy to become the largest manufacturer in the country.
The soft solid versions of pure gel such as Technogel are typically used in thinner layers because they have a very high compression modulus and are generally too firm for most people in thicker layers. They are thermally conductive and because of their high gel content they work well for this but they lack ventilation and humidity control so they usually come with surface modifications both for comfort and performance and to improve ventilation. A forum search on Technogel (you can just click this) will bring up quite a few more posts that have more information about them and includes some feedback from members.
Kingsdown (in their Blutek line) and Sherwood bedding (in their Evosleep line) are a couple of other manufacturers that use soft solid gels in some of their mattresses.
The gel foam segment is still dominated by marketing information, and “me too” designs and a fair bit of hype though which in most cases has some partial truth but is not especially informative or accurate about it’s benefits or the specifics of the materials.
Overall though … gel memory foams tend to sleep a little cooler than “regular” memory foam although the benefits often don’t last over the course of the night (again depending on the specifics of both), be similar in durability compared to the same density of “regular” memory foam (except for those that use larger “chunks” that can migrate out of the material easily), can add some extra support to the memory foam, and can add some cost to the base material as well. Over time and as new generations and variations become available the performance benefits of these types of foam appear to be gradually improving but it’s difficult to know how much is hype and how much of the information is reliable outside of retailers or manufacturers that will give you accurate “real life” information based on their experience (even if all the technical specifications outside of density aren’t available). There are also many differences between different gel memory foam materials in terms of density, formulations, performance, and cost and in some cases some of the better quality or higher performing versions that use higher percentages of gel or more costly manufacturing methods or compounding formulas and have greater “real life” performance benefits but are more costly can be “overwhelmed” by similar looking but much lower cost gel memory foams that don’t perform as well or don’t have the same benefits as their higher cost competitors.
This is similar to “regular” memory foam where there are many lower cost and lower density “cheap” memory foams that are being advertised as “just as good” as higher quality and more costly versions of memory foam that have greater durability or performance but of course they aren’t and in many cases consumers have come to believe that “all memory foam is alike” when of course it isn’t. The same is generally true of the emerging group of gel memory foams as well where similar looking products can have a range of differences that aren’t always obvious.
Phoenix