Bed Base - Slatted or solid?

We are in need of a new bed. Not only is our current one about 18 years old, my sister and brother-in-law are coming to stay with us on a year long holiday from USA when they both retire in July.
Our current bed still gives us a comfy night's sleep but it's time for a new one so we have found a mattress we find very comfortable in Dreams (Therapur ActiGel Rejuvenate 2200) but it's a new bed base I'm struggling with.
Our current one is a drawer divan with a solid top that has some sort of springs but because our bedroom is small, we can't open or use the draws near the head of the bed so we are looking at the bases that you lift up and store inside,
Most of the ones I've found have a sprung slatted base so I was wondering if other people have this type and what do you honestly think about them?

(My husband and I do still do bedroom gymnastics but not very often and not very energetic!)