Hi kimbeck,
The Dreamfoam mattress uses more costly materials (blended Talalay is a higher cost material than synthetic continuous pour Dunlop) and also provides the option to choose the firmness of your comfort layer but the cost of the materials may be less important than how well you sleep on a mattress and in the end I think that it would really boil down to which type of latex you prefer and which one you are most confident you would sleep best on in terms of PPP (Posture and alignment, Pressure relief, and Personal preferences).
Dreamfoam’s sister company Brooklyn Bedding also makes a mattress called the Tri-Comfort latex which uses two 4" zoned layers of the same type of continuous pour Dunlop latex as the Ikea Myrbacka which also gives you the option to choose the firmness of both the comfort and support layers and also gives you the chance to further customize the mattress after a purchase based on your sleeping experience by either reversing the layers or exchanging a layer for a different firmness level but it’s also in a little higher budget range.
Which of your final choices would be best for you will really depend on the parts of your personal value equation that are most important to you since all of them are good quality/value choices.
Phoenix