Hi Sam, 
 
Thanks for your question. 
 
We would need to know your body weights in order to discuss suitability as the Origins Pocket 2000 is quite a firm feeling mattress in terms of support;
 

 
Zip and Link's are ideal where you might struggle to fit a one piece mattress into the property, where you might struggle to flip and rotate a one piece mattress, where there is a big difference in body weights or where one user tends to disturb the other. 
 

 
This model has a medium upholstery providing a slight sink into that top layer but not too much. 
 
I couldn't really comment on retailers like Harrison as most retailers out there don't disclose how they construct. 
 
What's worth bearing in mind is that we do say spring count is less important than the fillings (comfort layers). As long as you have the right tension to support your body weight I would focus on the fillings. 
 
I hope this has answered your questions fully but if you do have any further queries please don't hesitate to contact our office on 0161 437 4419.
 
Kind Regards, Lee.