Hi somewhatrelaxed,
I think that doing some local testing if you are considering an online purchase can be a very good idea but it’s also important to keep your expectations realistic as far as how closely a local mattress and a mattress sold online will “match”. Post #14 here talks about some of the challenges involved and in most cases I would use your local experiences as a guideline or approximation rather than thinking in terms of “matching” the feel and performance of an online purchase.
Every layer and component (including different covers and quilting) interacts and affects every other layer to a larger or smaller degree degree so differences in the specific type of materials, the ILD (firmness or softness) of the layers, the type of cover and quilting, and the thickness of the layers are some of the ways that two mattresses appear to be similar initially may in fact feel quite different from each other although if most of these are similar then the odds are much higher that they will “approximate” each other.
In general terms … the Brooklyn Bedding Ultra Plush is a latex hybrid that has 3" of latex (in your choice of ILD) over a high quality polyfoam base layer (I don’t know the ILD of this) and then 1.5" of quilting foam in the cover. The closer you could come to these specs (including the ILD of the latex comfort layer you choose) the more likely it would be that a mattress you tested will be similar but every difference between them … known or unknown … can make a smaller or larger difference. The biggest part of the “feel” of a mattress will come from he upper layers (heavier people will feel more of the upper layers than lighter people).
I don’t keep records of the specific mattresses or their construction that are sold by each store or manufacturer but some of the better options or possibilities in the New York city area are listed in post #2 here and there is a more categorized list with more detailed descriptions of many of these in post #7 here.
You would need to call each of these whose website indicates that they may carry latex mattresses to see which of them carries a latex hybrid mattress on their floor that has a similar construction (at least in terms of the thickness of the latex top layer and with a high quality polyfoam base layer) and then you could visit the ones that carried something similar for your testing. This could then be a guideline if you find that Brooklyn Bedding is better value than your local options and you could use your testing as a guideline in your conversation with them to make your comfort choice.
Just as a thought as well … because of your weight differences … you may want to consider a “split layer” on top which would allow each of you to accommodate different needs and preferences and make different comfort choices on each half of the mattress. This is not an option with their Ultimate Dreams Ultra Plush but it is available with either the Eurotop mattress (which also offers a comfort exchange if you make the wrong comfort choice) or with many of the mattresses that are sold on their own site as well.
Phoenix