Hi starfishtwo,
I can’t speak from personal experience because I don’t own a Christeli but I can make a few comments that may be helpful. Just in case you haven’t read it yet … the first place I would start your research is the tutorial post here which has all the basic information, steps, and guidelines that can help you make the best possible choice.
I can’t speak for any other site of course but I pay little attention to mattress reviews which are among the worst ways to choose a mattress (see post #13 here) and focus much more on the transparency of the manufacturer and the quality of the materials in the mattress along with the other parts of “value” that may be important parts of each person’s personal value equation.
They used to offer an optional add on where you could purchase a return/refund policy for $29.95 but they now only offer an exchange so if you don’t like memory foam and an exchange wouldn’t make a difference you would need to sell the mattress on your own. This means that I would make sure you are comfortable with memory foam and have tested memory foam mattresses locally to make sure you are familiar with the material and like it. Memory foam is certainly not for everyone.
I would also be aware that there is no material that is inherently “good for backs”. When you have back pain then the design of a mattress and how good a match it is for your body type and sleeping style in terms of PPP is much more important than the materials that are inside it. A mattress that keeps you in good alignment in all your sleeping positions over the course of the night is the best option for your back … regardless of the materials it uses. the type of materials are a personal preference. Some of the other online memory foam providers linked in the tutorial post do offer a return policy which may be an important part of your personal value equation if you aren’t sure how you feel about memory foam although I would strongly encourage you to do some local testing on memory foam mattresses.
Phoenix