On the isotope case, I've found a flaw in the design.
At the front there is a removable mounting wall, for screwing things like cd-drives to. I'm refering to the small one on the left, as you look at the case from the front. If it was the length of the case, it would reach where the PSU fixes to the case.
Due to the size and shape of the isotope a modular PSU is best, to save space. Even with one 16cm long, the 2cm gap between it and the 'bracket' wouldn't be enough for a connector to fit, as there's only an 18cm gap for the PSU, including modular connectors.
I was going to RMA an enermax galaxy 1KW psu, as it's 22cm long, and was gonna swap it with the coolermaster M1000 which is 18cm long.
Looking at how it'd fit in the case though, there's not even space for this psu either as the end of the 'bracket' would have to share the same physical space as one of the connectors on the psu, which I'm sure you understand is impossible.