I am only going to address the travel agent question and 8 speed question.

I did have one problem with the travel agent on a tour last summer. I usually use fenders, but did not bring them on this trip because they did not fit in the S&S case. My rear brake and travel agent collected a lot of mud on an all day rainy gravel road ride. Enough mud, that when I actuated the rear brake, the brake stayed stuck in brake mode and did not release. I had to stop, get off the bike and pull the brake arms apart manually. Later, bought a brush and used a lot of water at the campsite to clean the bike, and especially the brake and travel agent. After which it was fine. If I recall correctly, I also put some chain lube on the travel agent bearing and where the wheel rubs on the plate behind it too.

That one bad experience has not caused me to avoid them, I installed one last month on my newest touring bike on the front brake (rear is disc) and I continue to use them on both wheels on my expedition bike. I mention my muddy day problem because if you are not using fenders, you may want to keep a close eye on them on wet days.

They do not have the best bearing (none) so a bit of dry lube on it can improve it a lot. When you first install them, I think it also helps to put some tension on the brake cable, perhaps a velcro strap around the brake handle and let the cable sit that way for several hours. That helps the cable take the new shape where the cable bends on the wheel. I think doing this makes them work better faster.

On the eight speed, you said it was Dura Ace eight speed. If I recall correctly, the eight speed Dura Ace had a different cable pull than the non-Dura Ace Shimano rear shifters. Thus, if you match a eight speed Dura Ace shifter and non-Dura Ace rear derailleur or cassette, you may have difficulty. My Shimano eight speed bar end shifters (SL-BS64) have a sticker that says that they are not compatible with Dura Ace. (For more info, google it.) Just giving you a heads up that you have to be careful on compatibility issues with your eight speed Dura Ace shifters, I am not saying you should not use them.