Mini DC Delta 50-820 preliminary design input, please?

[Canuck Bob]

My shop is modest, small 240 sqf, but equipped with a decent array of dust producing tools with a 12 1/2 inch Delta planer.  My little compact DC is a 1/4hp (6A), rated at 500cfm (hoping for real world 375-400cfm for system), and sits on the floor and uses a 4" inlet. The system will travel from tool to tool.  Upgrading is out of the question.

My first concern is balancing the size of the system for maintaining as much collection efficiency against a sensible dust bucket capacity. 

Is it correct to assume a system with a larger baffle and dust bucket capacity than the optimal size can quickly rob efficiency with a marginal blower?

I'm assuming the tophat design would be preferred?

If you were building to these specs how would you size the baffle and bucket in diameters and gallons (litres)? Please indicate baffle sizing for the tophat and the original type.

[Canuck Bob]

Edited OP to reduce the verbal overload!

I've decided on a 10 gallon, 40L, small steel drum in my shop.  It measures 12"D X 22"H.  Unless advised otherwise the initial plan is a tall top hat with 4" ports.

Searching has taught me that TBaffle design is very hard to design for someone else.  Certain DC units have been done many times and much easier to to research unlike mine.  I'm going to look on this as an experiment, OSB before Baltic Birch.