
Now, that of course has got nothing to do with historical accuracy whatsoever. But to fit the setting of the play a suitably medieval look is still required. You will find that especially the younger audience will notice if your kit is odd, for example if the helmet is the wrong shape for the period or if your elbows don't match your knees...

GDFB has been a boon to us here because more often than not they portray the right shape for the object they intend to copy. Of course a lot of them are probably not accurate at all but they don't have to be. They just have to play the part from a distance. Important is only that everyone can recognize the Bold Slasher as a 13th century knight (because we decided it'd make a suitable costume) and that the actor playing the part gets to survive until lunch break relatively intact.
I see GDFB kit as very durable and hardworking kit for a serious performer. But not necessarily a living history buff. After all, Mummer's Plays are an entirely different ball game.

I've never seen a GDFB helmet fail. And being quite thick you do get a lot of metal for your money. If you don't mind knocking the occasional dent out they last pretty much for a lifetime, if you wish to keep them. Go for it!
And by the way: I am thinking GDFBGlobal here, which is mostly the same but has generally more up-to-date products and a larger stock holding (I think).