I'm actually fairly happy with out 8 gal biocube even though I just use it as a quarantine/frag tank now that we have the bigger ones. I don't find heat or evaporation to be an issue, but it's not in a hot room (only about 75) so I think that helps.
We did have one ballast go on us a couple months after buying it and we contacted the company and they sent a replacement no problems.
When it was set up as a nano reef everything in it was really happy and growing well.The filter cartridge is a little sticky to get out but that's probably "user error" rather than a fault
I would recommend them, and I like that they're glass rather than acryllic...I'm hard on the algae and acryllic wouldn't work for me.