Hi Canuck,
You will find some of my more detailed thoughts about the Tempurpedic (and the memory foam market) in Post #5 here … Post #20 here, … and post #2 here.
While general comparisons between brands (rather than specific mattresses) can be more misleading than helpful … it would be “somewhat” fair to say that the iComfort is most comparable to the Tempurpedic Cloud line.
In terms of value … it’s difficult to compare because different people have different ideas of what they value besides just price. Of course a mattress needs to provide the basics of pressure relief and alignment (the 2 main functions of a mattress) but the intangible preferences such as “feel”, breathability, temperature, ease of movement, motion isolation, durability, natural ingredients, how a mattress looks, and many others have a different level of importance in each person’s “value equation”.
In essence … the Tempurpedic will probably be more durable and is a more 'known" quantity in terms of long term performance but the “feel” of the iComfort is very popular (as evidenced by its success). I don’t think either of them represent good value though when making an “apples to apples” comparison with other options … particularly when comparing with local manufacturers that make mattresses that use equal or higher quality materials and sell them at a lower price. The comparison itself is between lower value and lower value.
Post #26 here will give you an idea of the different types of gel memory foam which are appearing in the market. An example of a local manufacturer who (among others) makes a higher value gel memory foam mattress is here.
So the “best” answer I could give you is that they both represent a lower value choice for different reasons and that I would have real difficulty if I was forced to choose between them. I would personally be looking in different directions.
Phoenix