Ok I just cooked a practice turkey, see brining thread in brined meat
we ate all the white meat off one side last night and I stripped all the dark meat off that side tonight, and that pure meat without skin weighed 816g, so from a 7kg turkey including giblets I get approx 1.6kg manually recoverable dark meat (after cooking). This includes meat from the carcass that I class as dark meat: oysters, intercostal muscle, neck, but only what I could quickly and easily pull off with my fingers. Edit: that also included wing meat. If I'd had read your post again before stripping I'd have weighed just the thigh and leg meat on their own. I'd guess 1.0 to 1.2 kilos cooked dark meat from a 7kg bird. If you like, when I do the other half I can give you a more precise estimate
Hope this helps,
Dave