can i install a push pull 4 fan corsair h100 on the top 2x120mm fan location ?

i'm very curious, cause the haf-x can take it nicely and still enough room for the motherboard clearance...

Yes. Easily.
The build I did with a thicker radiator (35mm XSPC as opposed to the 27mm of the H100) had the pull fans mounted on top the chassis (under the top panel), with the push fans mounted in the usual position inside the chassis. I used a 5mm thick spacer/vibration dampener with both sets of fans also to minimize the cooling "dead spot" behind the fan hubs.

Cases always have pros and cons. but one has eluded case developers since the dawn of the computer - air filters! you make lots of holes for cooling which allows LOTS of dirt, dust, dog hair, etc... make a case that has a washable air filter!!!! all the cooling in the world wont help if the fans are clogged and wont rotate!!

Yes when I first saw that handle I too wondered "who carries a desktop"? But speaking as someone who has carried 5-9 laptops around the country to do trade shows & demos. This may be a very good alternative. I'm considering kitting this out with 64GB & 9 drives, to run a few virtual machines. I'd have the whole data centre in 1 box. Perhaps less fault-tolerant, but easier to get power & way better disk performance.

My Antec 900 Two has air filters. This case has air filters. The HAF X has air filters, the HAF 932 has air filters. Corsair Obsidian cases have air filters. I could go on and on. Perhaps you've only purchased low quality cases in your lifetime, but cases designed for lots of airflow have had air filters for years.

It's kind of silly to use a passively cooled Megahalem in the thermal test. Noone owning a case like this is gonna buy a Megahalem and not have active cooling on it.

Also it seem awfully fishy to get 17c drop at load on a passively cooled Megahalem with 2 front Case intake fans being the only means of fresh cool air which the top fan is blocked by 2 drives and a videocard. That in no way is going to have any sort of direct airflow to the cpu heatsink to make an incredibly 17c drop from idle to load.