[Warnberg]

1) Is it any good and will it sustain the life I plan on keeping Mixed reef with calms take will be 48x32x28

I have seen this fixture over friends tanks and they seem to be fine.

2) Does anyone know if you could replace the bulbs that come with it sunpaq to XM bulbs and how will the bulbs fair with their ballast.

I believe you can use double ended XM bulbs in that fixture, but I would check with the manufacturer first as it has a magnetic rather then electronic ballast

3) Should I just go with MH retro inside my canopy.

I would wait until I got my canopy and measured it. I also like the idea of a retro kit as if something goes wrong you can always just change out that piece.

4) The retro will be using a lumenma 3 which measure 11x11.5x5 and 4x54 T5 retro kit. My canopy will be 12" tall . Don't know if I'm going to have enough clearance with the retro in the canopy that size can anyone advise on that as well.

Sorry cant help you with this one