Hey Andrew G,
I'm not aware of the TRUE's base being uneven anymore but if it did have a slight convex base I think that line would be the same direction as the fins, honestly though I don't think this is something you should worry about!
In the example above I mentioned using Fan-Filters on the cases side panel 120mm Fan-Space and the rear 120mm Fan-Space *if* not using the rear 120mm fan.
I dare say if one is using a rear 120mm exhaust you wouldn't need to use a fan filter as the air-pressure travelling in the opposite direction should keep the dust out!
As to your suggestion of reversing the cases airflow (having the rear and top fans blowing in and the front case fans as exhausts) that is something I have considered although due to time constraints not tested it myself. You would deffo need fan-filters on the rear 120mm and top 140mm fan if running a reverse Antec 300 airflow, you would also not be really using the cases superb front-intake fan filters (or at least they would be collecting dust from the inside so probably best removed!).
I think using the classic front intake/rear exhaust is probably best for most Antec 300 users, although to keep the case interior dust free you would need to add at least one 120mm fan filter on the cases side-panel 120mm fanspace otherwise that will hoover in a fair bit of dust.
I'm also not so sure the rear/exhaust 120mm fan follows good airflow principles as its creates a contention of airflow against the top 140mm exhaust (i.e a tug of war which way the air should travel!).
Truth be told I have found Positive-Airflow works best so far in the Antec 300, as I'm sure most are aware to create Positive air-pressure you need to ensure there is more air being blown into a system than exhausted, that is the primary reason I took out the single rear 120mm fan leaving just a slow turning 140mm roof exhaust and to some extent the PSU's slow turning 80mm!
Now most of the air in my system is being sucked in via the two front 120mm fans and exhausted via the roof. I may well build/source two 120mm Fan Space sized blanking plates and seal up the case side 120mm fan space and the rear 120mm fan space and save myself some hoovering! . . I don't think sealing up these two vacant fan spaces will have a significant impact on cooling if you pay attention to organising your airflow!
Lol, its amazing how much you can talk about such a tiny subject!
The Antec 300 Rocks, wish I bought more when they were selling for £30!
