Hi JulieS,
[quote]The Liberty is about $100 more. I am leaning towards the Aloe Alexis, and like the idea of being able to replace the latex but my husband is VERY concerned about buying online. He does not think it is a good idea for a number of reasons. #1 We can’t test it out. #2 the mattress comes in parts that you have to put together.
Do you have any words of wisdom for our dilemma? [/quote]
You are certainly looking at two very good quality/value options 
Both of the mattresses you are considering are very similar (assuming that you choose the same layer firmnesses in the Aloe Alexis) and any meaningful difference between them would likely be in any differences in the thickness and firmness of the polyfoam support core.
When you can’t test a mattress in person then the most reliable source of guidance is always a more detailed conversation with a knowledgeable and experienced retailer or manufacturer (such as Brooklyn Bedding/Dreamfoam Bedding) that has your best interests at heart and who can help “talk you through” the specifics of their mattresses and the options they have available that may be the best “match” for you based on the information you provide them, any local testing you have done or mattresses you have slept on and liked that they are familiar with, and the “averages” of other customers that are similar to you. They will know more about “matching” their specific mattress designs to different body types, sleeping positions, and preferences or even to other mattresses that they are familiar with (such as the Liberty Eurotop) than anyone else.
Once you have had your phone conversation with Brooklyn Bedding/Dreamfoam if it turns out that they are virtually the same in terms of comfort and PPP (Posture and alignment, Pressure relief, and Personal preferences) then your choice will really come down to the “peace of mind” that may be involved in choosing a mattress that you have tested in person or how you feel about buying a mattress locally (the Liberty Eurotop) vs the options that you have available to fine tune the firmness of the latex layers after a purchase by rearranging or exchanging them (the Aloe Alexis). Which one would be the “best value” for you will really depend on the parts of your personal value equation that are most important to you.
When you are down to finalists that are all choices between “good and good” (which you are) and none of them have any lower quality materials or “weak links” in their design (which they don’t) and if there are no clear winners between them then you are in the fortunate position that either of them would likely be a suitable choice and post #2 here can help you make a final choice based on your local testing or mattresses you have slept well on, your more detailed conversations with each of them, your confidence about PPP and the suitability of each one, their prices, your preferences, the options you have after a purchase to fine tune the mattress or exchange or return the mattress or individual layers, any additional extras that are part of each purchase, and on “informed best judgement” based on all the other objective, subjective, and intangible parts of your personal value equation that are most important to you.
In the end this is a choice that only you can make because there is no clear “better or worse” between them other than your own criteria and preferences.
I’m looking forward to finding out what you end up deciding!
Phoenix