I have a nanocube...not exactly the same, but similar enough. The only difficulty I could see is maintaining stable parameters and keeping nutrients low...which is an issue in any "nano" sized tank.
I think if you plan things out you shouldn't have any problem. I kinda jumped in and made equipment upgrades as I went along, but a good HOB protein skimmer and a couple dosing pumps went a long way. I added a gfo reactor only recently and I have zero complaints about my current system...other than a lack of space for more coral.
I have a 28g JBJ and it's been my best/easiest tank so far! The max bioload I had for a good 6 months was 2 clowns, Coral Beauty and a mandarin. The Coral Beauty has since been moved but the tank continues to be awesome! I have everything from SPS to softies and everything in between.
The name. Any small all in one is about the same. Keeping parameters in line is more of a hassle, but not that bad. Things get out of whack a lot faster in the smaller water volume.
I personally like the JBJ Nano WAY more than the Biocube. I just felt the Biocube was cheaper in quality when I put my hands on them and liked the fit&finish of the JBJ better. I also love the wavemaker the JBJ comes with, that's the biggest difference to me. The JBJ comes with two return pumps to 2 different return nozzles and a wavemaker that can be adjusted for alternating timing for the pumps. That was the biggest selling factor for me.
The biocube is also a little wider (20" vs 18" ) ...whereas the nanocube is taller (22" vs 19" ) . Pretty minor difference.
I agree that the more significant difference between the 2 is the dual returns and wavemaker in the nanocube. That being said, I pulled the wavemaker and have my returns running continuously; I do appreciate being able to direct a good amount of turbulent current behind my rockwall though.