Biocubes are known for blowing ballasts. While I think their design and look is superior to nanocubes I wouldn't buy a stock one.
An example:
http://www.reefcentral.com/forums/showthread.php?s=&threadid=1422508
If you want stock lighting I would do a nanocube, if you decide on a nanotuners mod I would go with the biocube.
My stock nanocube:
My nanocube with the nanotuners 108W custom hood (With the 108W hood I kept Gorgonaians and some easy SPS like Monti Digi's and birdsnests though the color wasn't the greatest)
My nanocube with the 150W Sunpod over it (Removed the hood), some Aquapods come with this lighting option
I really can't say enough good things about nanotuners. When I ordered my hood they built it the same day and got it shipped the same day. I would call them and ask them what their opinion is of the Biocube Ballasts and if you buy a Biocube tank with one of their lighting modifications is there a lesser risk of the ballast dying. Maybe they have alternate ballasts they can or do use.