Hi Paul,
You can read a little more about Magniflex in post # 6 here and post # 2 here and post # 3 here and a forum search on Magniflex (you can just click the link) will bring up more information and feedback about them as well.
As for Zedbed, the reviews on google give them a 2.4
Yes, building your own mattress is more research and trial and error, but if you have time and patience to do it, you may end up with a superior product in the end.
All the best