Hey Lone, you know I'm a fan
Combined with my experience with the Realan e-i7 case, I'd like to humbly make a set of recommendations for your next iteration:
The combined benefit of these changes would be ability to cool and power more powerful CPUs.
- I believe the front fan positions are not optimal. Airflow in that direction is broken by the DIMMs and it's clashing with the airflow from the GPU. So, I recommend to move the fan positions to the top of the case, increasing the height by 15mm for thin 92mm fans.
- Then, the space in the front can be used to install a FlexATX PSU, exhausting upwards (so the top fans quickly discharge that hot air out of the case). You would, of course, have to provide an internal extension cable as an optional purchase for users who would prefer this option. I believe FlexATX will become more and more popular, with more and more manufacturers coming up with optimized/silent/modular designs. It's already started happening...
- Two more fan locations at the bottom, for two 92mm fans, for those users that may want to take their stock fans away and install 92mm fans here for quieter and better performance.
Another, rather drastic, idea I have requires use of PCI-E riser cable to support ITX (not LP) cards below the motherboard but elevated from the motherboard plane. The ITX GPU would be elevated to give space for a FlexATX PSU right below the motherboard. The ITX GPU would have its fans facing the side panel. Even including the 15mm fans on top of the case, I reckon case dimensions of 300mm height, 200mm depth, 100mm width would be viable. Final result is a 6-liter, very small foot-print case that supports FlexATX and ITX-size GPU (as well as quite tall CPU coolers). I believe I am correct to observe that such a case would support DTX-size motherboards as well...
Edit: For the crazy-factor for this last idea, I believe an internal bracket can enable a 120mm AIO (with a slim fan) to be installed on the side panel. This would certainly require AIOs with low pump/block assemblies and flexible tubing...
IMO there are already ton of cases supporting such features. However there are not enough decent amount of cases like L5. It is a unique case which addresses different needs. Some people just wanna have a silent and small case for their daily works or media centers. There are people would like to run only an APU or LP GPU supported case for light work. These implementations you offered mean ignoring these people and making L5 an ordinary case among other hundred examples. Nevertheless I agree with you about case airflow can be improved in the future versions.