Hi ewmyers,
Welcome to the Mattress Forum! 
The difference would be the option for adjustability, but mostly in the quality of the wood being used and the subsequent ability to maintain its bow and flex consistently and not flatten out over time or delaminate. The BE and FloBEds systems you mentioned would be higher quality than the Lonset, which should be apparent when you see the items in person at IKEA.
You can see some thoughts about flexible slat systems in general post #2 here and the posts it links to. Because a flexible slat system is an “active” part of a sleeping system (just like any other layer or component either in, under, or over a mattress that flexes or compresses when you sleep on it) … the only reliable way to know whether this system would work for a particular mattress would be testing the particular mattress upon the particular slatted system you were considering.
There are links to some tension adjustable slatted systems of which I am aware in post #1 here.
Phoenix