Don't sweat the moving mess, I just did it myself eight months ago

For a freshwater tank I don't think, personally, I'd want to do it in a biocube. I've never been thrilled with how they look overall, between the curved glass and all the ABS plastic. Too distracting. From a technical standpoint though I;m sure it would work well.
The solana could be made to work. Yeah, I do think you're right and the MH hanger could be modded to work with a PAR38/PAR20 bulb. Interestingly enough I'm familiar with the reef tank the guy in the link used to have.
Another alternative you might be interested in are the Mr Aqua cube tanks marine depot carries. THey offer a 12" 7.5 gallon cube very cheap, and an 18" 25g one for $99....
http://www.marinedepot.com/Mr._Aqua_Cub ... RC-vi.htmlThey also offer a really nice elm hardwood stand for those, if you decided you wanted to use a stand.