Right now there are 10 (with 5 more in the Pipeline IIRC) Marder A5 in Afghanistan as well as 3 Panzerhaubitze 2000.
No Leos but some politicians and soldiers want them there. There are also other voices that say that they are too heavy for the terrain.
The Leo IIs in Canadian and Danish service cope well with the environment. The Danes use the Barracuda system to keep theirs cool and the Canadians adopted this too recently (including these lovely umbrellas for the TC/loader

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Leopard IIs are also in use with Spain, Greece and Turkey in some very hot and dusty environments including the Spanish posessions in Northern Africa. The Danes and others tested their Leos for example in Spain.
The Leo performs well in such environments and has no more problems with heat and dust than can be expected as machinery of every kind is going to suffer in extreme environments.