use of struct vs class

[mark via Digitalmars-d-learn]

I have this struct (with details omitted ... for brevity):
struct Deb {
    string name;
    ...
    RedBlackTree!string tags;

    void clear() { name = ""; ...; tags.clear; }

    bool valid() { return !(name.empty || description.empty); }
}

I plan to store >65K of these (with potential for growth to 
>250K) in an AA:

Deb[string] debForName;

I plan to populate debForName by reading data files (actually 
Debian Packages files) like this:

Deb deb;
auto file = File(filename):
foreach(line; file.byLine) {
    if (line.empty) {
        if (deb.valid) // end of package
            debForName[deb.name] = deb; // XXX
        // else report incomplete package
        deb.clear;
        continue;
    }
    ... // populate the deb
}
if (deb.valid)
    debForName[deb.name] = deb;

I'm assuming that line XXX will copy the Deb including the tree 
(which as usual I'm using as a set -- I really miss a set class 
in D!). Will this work (I'll find out myself next week when I get 
further, but D experts can likely tell from the above).

Should Deb be a class rather than a struct?