Hi Gdub42.
Congratulations on your purchase from SleepEZ. 
I am interested to hear how the topper/OMF current mattress combo works out for you.
A topper in a guest bedroom is going to need to accommodate multiple BMIs and sleeping positions.
Something on the medium - softer side is going to be more comfortable. Dunlop does make a better sitting surface and Talalay is a better and “livelier” sleeping surface so that’s a tough call on which way to go.Talalay is also going to be a better option for adding comfort to the mattress in your guest bedroom. Dunlop has a different “feel” and performance than Talalay and is less lively or springy. You can see a comparison between them in post #7 here but your own experience is really the only way to know which one you prefer with any certainty. Some people would notice more of a difference than others with transition or support layers that used each material if the top layers were the same type of latex because you will “feel” more of the upper layers than the deeper layers … at least when you first lie on a mattress
You may wish to make your decision on what softness to buy based on your own sleeping experience once your new topper from SleepEz arrives. You’ll have a few more data points at that time and it would be easier to fine-tune your purchase based on real-life experience.
Keep us posted.
Phoenix