Hi resilience,
Thanks for the kind words 
There are quite a few factors that either by themselves or in combination with each other can lead to a mattress sleeping hotter or cooler. Post #11 here and post #2 here have more about the different factors that can affect sleeping temperature. The new types of gel foams can certainly have an incremental effect and for some people this can make a difference (if they are sleeping on the gel foam and it is not too deep in the mattress). Because gel memory foam is still memory foam though and will allow more sinking in than other faster recovery foams and conform more closely to the body … some people can still tend towards sleeping hot with them (which explains the comments you will read where some people say it makes a difference and others say it had no effect) and need to “correct” other factors as well to get to their preferred sleeping temperatures.
I like adjustable beds and have one myself but for most people it is a nice luxury rather than a necessity. They can be useful (under the guidance of a health professional) for certain more “medical” conditions (acid reflux, some heart or circulatory conditions and others) and in some cases for pure back sleepers can be pressure or pain relieving and may even help with snoring if they are raised during sleep but for the vast majority of people they are best used flat while sleeping (for those who spend any time on their side or stomach) and the adjustable features are just a luxury for reading, watching TV etc. The best value that i know and a good reference point for pricing on adjustable beds is here (which is where I bought my Reverie Deluxe).
Phoenix