Hi Raistlin,
I doubt that you will find someone else that has slept on both of them (including the specific firmness choices you would be making) so it’s unlikely that other people’s experiences would benefit you much. Even if they had experience sleeping on both their body type, sleeping positions, personal preferences, or their individual criteria may be very different from your own and their experiences on a mattress in terms of PPP (Posture and alignment, Pressure relief, and Personal preferences) may be very different from yours as well. Using other people’s experience can be very risky when it comes to choosing which mattress is “best for you”.
You can see some comments about the Nirvana design in post #7 here. All the materials are high quality and there are no weak links in the design so from a quality perspective the design is great. From a suitability perspective it uses a more unusual design approach that has firmer materials on top and then changes the firmness of the deeper layers to add additional “give” underneath the latex. This would be similar to a “dominating layer” (see post #33 here and the posts it links to) and would also be similar in a way to say a 6" firmer latex mattress that uses a box spring underneath it to provide some extra give under pressure points. These types of designs create a firmer sleeping surface with a much more “on the mattress” feel with some additional give and softness underneath the firmer layers. A forum search on Shovlin Nirvana (you can just click the link) will bring up more information and feedback from some of the forum members here about it as well.
The Aloe Alexis on the other hand has a more traditional approach that uses progressively softer layers as you go from the bottom to the top so you would have a deeper pressure relieving cradle and softer feel on top of the mattress and a more “in the mattress” feel in most cases. Differences in design such as these aren’t “better or worse” and are more of a preference choice where some may prefer one type of mattress and others would prefer the other. A forum search on Alexis (you can just click the link) will also bring up much more information and feedback about it as well.
In terms of comparing them I would start by reading post #13 here which has more information about the most important parts of the “value” of a mattress purchase. The priorities are always suitability (how well you will sleep on the mattress), followed by durability (how long you will sleep well) followed by all the other parts of a mattress purchase that may be important to you that you can use to make meaningful comparisons based on the parts of your personal value equation that are most important to you.
In terms of suitability the most effective way to predict your sleeping experience on a mattress in terms of PPP is with careful and objective testing. While this isn’t always 100% accurate of course … if you test carefully it is the most effective and reliable approach. If you can’t test a mattress in person then a more detailed conversation on the phone with an online retailer or manufacturer in combination with local testing on mattresses that have some similarities to what you are considering is the “next best” approach. They can use your experiences and the “averages” of their customers that are similar to you to help you make a choice is the “next best” approach (see mattress firmness/comfort levels in post #2 here). The better the information that you provide them the more you will help them to help you make the best possible choice out of the options they have available.
In terms of durability they both use high quality materials and there are no weak links in either of them so this would be a wash.
If you are confident about the suitability of your finalists in terms of PPP (or the options you have to fine tune it after a purchase to make it suitable) and they both don’t have any weak links in their design or materials relative to your budget range (which they don’t) and there are no clear winners between then then you are down to a choice between “good and good” and your final choice (see post #2 here) would really come down to “best judgement” based on all the parts of your personal value equation that are most important to you and your odds of making a successful purchase that you will sleep well on for a long time and that you consider to be good value are very high either way.
Phoenix