...only gold, copper and silver conduct heat better...
Yes, silver/copper/gold in that order... but among common metals used to make such things:
| 1 | Copper | 223 |
| 2 | Aluminum | 118 |
| 3 | Brass | 64 |
| 4 | Steel | 17 |
| 5 | Bronze | 15 |
And, yeah... SS has more thermal mass, so stores heat better, aluminum has more thermal conductivity, so dissipates heat better... so the SS f8 behaves just as you said. It will eventually get pretty hot if you burn a lot of rope over it, and will take longer to cool down. A splash of beer over it... er... water.... will cool it down instantly, though. It really hasn't been an issue, and the SS holds up to the abuse better than aluminum, by a long shot. I've found that aluminum devices get real hot, real fast and that the SS ones take quite a bit longer to get too hot to handle. Black anodizing would only make a metal absorb radiant heat faster, so doesn't improve anything in this application.
The tradeoff for the high wear resistance is weight, of course. That will be very important to some folks, not so much for me. I'm never in that much of a hurry, so tend to just bundle stuff up on the ground and pull it up into the tree with a haul line when I need it. I'm no production climber, I'm far too old and slow to give a rat's ass about how long stuff takes to do.
I think for climbing applications, the big SS ones aren't very practical. I doubt if a small, aluminum one would do any serious damage to a 1/2" rope for occasional use. Especially in these applications where it is just providing some (not all) of the friction in the system. It is a small bend radius, though. There needs to be a small, aluminum device for just such applications that has nice, fat bend radius parts for the rope friction. I need to think about that some more. Actually, DMM and RE and all those other companies should think about it more.
