Be sure to study the overlay system before you buy so that you know what you are getting. These are the "heavy" type overlay system panels onto which one can directly lay tiles or solid wood flooring. Polyplumb also have a light version which requires a ply layer before tiling. I am directly tiling over these panels and so these are great for my purpose.
I've now recieved 15 of these packs with more to order. At first the panels were delivered in boxes far too big which allowed the panels to fly around inside and get damaged (usually broken in two). Fortunately, for me, I was able to utilize the damaged panels in areas where cutting would have been required.
The latest batch have arrived in more appropriately sized boxes - I have yet to open them but hope that the packaging material has been wrapped around the panels this time so that they will all be undamaged.
If you can accomodate the additional floor depth and have the budget I would recommend fitting additional insulation boards under the Overlay panels (8-10mm).
Fitting the tubing in the panels is quite easy, plan the layout before you begin.