Hi sb,
While conventional wisdom would suggest that that wool that isn’t quilted would have a greater chance of shifting or bunching inside the mattress … this would also depend on the amount and thickness of the wool (which would also have a significant impact on the cost of the cover as well) because as they suggested thinner layers of wool would tend to “stick” to the latex. These types of issues would generally show up fairly early so if their experience indicates that they haven’t had any issues then I would take them at their word because they aren’t the kind of retailer that would say something for the sake of making a sale and then having an unhappy customer down the road.
Airflow under a mattress can be important with any type of mattress … not just latex … but it’s really a matter of “risk management”. Latex is more breathable than other types of foam materials and it also tends to resist mold and mildew and dust mites better (see post #2 here) so the risks with a solid surface would be less with latex than with other types of mattresses and it would really depend on someone’s risk tolerance, where in the range of risk they are most comfortable, and on the other risk factors that are involved as well (see post #10 here).
It would depend on the blend of latex as well as the firmness but post #2 here has some reference points for blended Talalay and 100% natural Dunlop that will give you some idea. Latex International also suggests here that their 100% natural Talalay is about 30% heavier than the blend.
I certainly agree that they make some very good quality/value mattresses 
Phoenix