so we've established that they're great for travel.
How can they weigh 8oz?

http://www.sandsmachine.com/

Even if they do, looking at the placement of them, aren't they getting placed beyond the butted section of a tube? Wouldn't that compromise your beautiful lightweight steel frame?
Looks like they can be welded into titanium also, heaven, but again, butt?
Does that mean you'd be better off using straight gauge tubing?

I have a bike with S&S Couplers which I am going to sell. They have been great and work as advertised.

I have no doubt that they add a good half pound or more to the bike. But who cares? That is not much.

Mine are attached to Foco tubing and I have had no problems.