"Greatly improved heat dissipation.." Tell me another one. Perhaps aluminum does soak up heat better than enameled sheet steel. But "greatly" is stretching the truth. Let's face it, Lian Li is a status symbol. It's nice that they don't cost two pints of RH+ any more, I must admit.
Aluminum has no clear advantage over steel. If you need to cut holes in the case panels to aid mounting fans for better air throughput, aluminum is easier to drill and cut. However, aluminum binds upon drill bits like nobody's business. Snagging a drill bit, at least in my experience can create a deformation in a flat surface instantly. And this is with steel! While left hand case covers are often not on display, I like metal that's supposed to be flat--to be flat.
Personally, I'd spend the money saved by avoiding a chi-chi aluminum case for more necessary improvements in basic PC configuration. Hey, it's your wallet, not mine!