I dont have this rta but just by checking youtube video I totally agree with you guys....this doesn't seem great for building with coils....and yeah no way u can have enough cotton with 2.5mm coil I think not even 3mm would be enough but that's not the end of the world....
Also with the bubble glass u lose the juice control and the way it's designed I think this rta really needs the juice control cause there is no place to dump the cotton and adjust the tightness of it...
Anyways the other straight glasses provide also a lot of juice capacity so it's fine...
Assuming you got all the orings on and I mean the atty is not missing anything I think that it can work good tho it's just tricky it doesn't look like bad design...
I like the looks of it...looks nice

The idea of clapton mesh is good in case u don't like mesh vaping but I am sure u can make it work even with coils just need a wire spool to be able to wrap your own coils and try different internal diameters