Had a look at the Lightweight in the RH Showroom when I visited last year. Got to say it looked as if it had been thrown together regardless of whether it was the prototype or not. However concept looked OK, and I can't see that a Lightweight would fall to bits if it was put together properly. Consistant edge distances, accurate rivet/fastener pitching, proper panel gapping and steer clear of the pop rivets (use avdels!) However as its a Robin Hood you might need to remake many of the panels to achieve this and it'll certainly keep you busy building for a good while!
NB: When finding fault with things that are rivetted together, remember an aeroplane is only 10,000 loose rivets flying in close formation!
Cheers
Nige