Hi Momma Mi,
I happened to own both talalay and dunlop latex, and they both have their pros and cons. As a general statement, they are both high quality materials. I happened to prefer the bed I have made of only dunlop, but there are aspects of talalay I like also and continue to try to see if I can have the best of both. I say this in that high quality dunlop vs high quality talalay is essentially a preference thing.
The "problem" with dunlop is that there are more companies making it, some better, some worse, and each has their own proprietary methods... So you're not able to compare dunlop nearly as easily. Whereas talalay is essentially only made by 2 companies, and therefore there's less variability. Talalay used in mattress X is likely the same as in mattress Y, and if you know the ild you prefer you can ensure it's identical. Dunlop can also have more variation within a plate, and more variability in firmness/softness...usually this isn't a problem, but can make ordering raw latex more challenging if that's your plan.
So... If you try a mattress and love it and it's a good match for PPP, and it has dunlop, and comes from a reputable mattress company... There's no problem. If you're trying to buy bare plates of latex, for instance to match the feel of another mattress, then dunlop is more difficult because you'd really need to ensure you get the same kind of Dunlop made by the same company to ensure an exact match.
Savvyrest has pretty good info on both, including the fact that it's really a preference thing. Now, I'd probably not go combing through amazon or alibaba trying to find the cheapest dunlop on the planet...I have always bought from the more reputable dealers, many such dealers are members of this website.
Talalay does cost more to manufacture, so it sometimes costs more to buy. This isn't evidence of better or worse.. Only different. What would make it better or worse is really your own preference and testing.
From a business perspective, there are excellent mattresses made with either or both talalay and Dunlop, and often the advice you'll get will really be an indicator of what kind of mattresses a particular mattress maker has more experience with. I.e. If they only sell talalay or Dunlop, and have for the past 10 years, it's quite likely you're going to hear about why its superior. It would be more appropriate to say that particular retailer has had a successful experience with that kind of latex and therefore prefer selling it - remembering that a different retailer may have had an equally successful experience with the other kind of latex too.
Basically they feel / perform different, and if you prefer the feel / performance of Dunlop, it's an excellent material that will do well for you.
I hope this helps!