Bottom line- I should have no issues running this scenery, however it might not be related to the FSDT KLAS, but to the region itself, or the new clouds from FSE.
The issue, as we explained several times, is not caused by the scenery alone. It's caused by the fact that FS9 can't load textures as efficently as FSX, that use multi-cores. So, in any case many textures are requested, the sim can stall. Textures can be called by anything: other scenery in the area, landclass, clouds, airplane liveries (user and AI), anything.
By resizing our textures we just lessen the demands from our side but, if you have lots of textures coming from anything else, enough to fill up what the sim can handle, it might just not be enough. That's why it changes depending on area, what the default scenery around looks like, what other addons are installed, and not everyone is seeing it the same.