My most recent set up in Savex L39 has two shampoo bottles for the main tanks. The second tank in the series (last one to empty) uses the clunk supplied by simjet and then into a very small hopper tank with a central pickup. This clunk will draw the last drop of fuel before allowing any air into the hopper tank. To date, I have not had any air bubbles in my hopper tank. I usually land with the second tank about half full/empty.

I think a UAT if used correctly without flaws works fine. But so does any other proper setup.