[Vala] Array of structs OR Array of classes

[JM <interflug1 gmx net>]

Hi all
For my app I have to move around datasets of some hundred to a few
thousand entries. These datasets contain several strings, some int (some
enums) and some uint.
I have the data in structs and from these structs I make arrays, e.g. 


struct myStruct {
    public string some_field;
    public int another_field;
}

    ...
    myStructArray[] = {}; //declaration with initalization
    myStruct a = myStruct();
    a.some_field = "some data";
    myStructArray += a;
    ...

For now, I am using a struct to handle each dataset. But it would also
be possible to do it with (compact) classes.

I heard that structs are stack-allocated and classes are
heap-allocated. 
Would there be an advantage/disadvantage for me to use classes instead
of structs? I need no additional features of these classes. 
I would do it like:

[Compact]
class myKlass {
    public string some_field;
    public int another_field;
}

    ...
    myKlassArray[] = {}; //declaration with initalization
    var a = new myKlass();
    a.some_field = "some data";
    myKlassArray += a;
    ...

Can anybody explain the differences between these two ways of allocating
memory and collecting the data? 
Regards
Jörn