Hi schmiggyjk,
I would definitely suggest testing latex if at all possible because it has a different feel from other materials (especially memory foam of course). TD-Max made some good suggestions of a couple of latex mattress manufacturers that may be available in your area and there may be others as well. If you let me know your city or zip I’d be happy to let you know of any in your area I’m aware of.
Yes … the metal frame foundations aren’t being made in Eastern King versions and the other sizes are only available until the supplies run out. Their regular version though is one of the very few KD foundations that have gaps less than 3" (its the only KD type listed in the foundation thread that does). The SleepEz price for this is the same as US Boxspring ($380 for the Eastern King) except SleepEz has free shipping so they are slightly less.
Latex itself is heavy of course but because these are layered … you can take each layer and move them separately (fold it carefully and put it in a plastic bag or box if you are storing it) which makes it easier. It’s the same reason they can be shipped through UPS instead of truck freight.
In terms of the durability of the different types of latex …I think post #2 here should help. In practical terms I would treat blended Talalay and 100% natural Dunlop in a similar ILD as being very similar in terms of Durability.
Normally it’s best to talk with the manufacturer directly about the options they have available but in this case I know that you can choose any layers you wish (including 2 Dunlop layers and a talalay layer).
Yes … I think a mattress protector is important. There are some tradeoffs involved in choosing between the different types (including how much they will affect the feel of the mattress). There is more information in post #89 here along with some links to various options.
Hope this helps
Phoenix