Can't speak for the UDS, but I've cooked on WSMs in temps as low as -20, Just gotta block the wind.
My guess? Since they operate on the same principle, it's a draw.
My Boys: Joseph (EI); Andrew (EE); Daniel (EE)
My Toys: 10 WSMs (B, C, DH, DA, EZ, DZ, EO, DU, DR, EE/DU mutt); Brinkman Cimmaron; Chuckwagon Cooker; 22.5" OTG (DT); Two 22.5" Bar-B-Kettles; One 18.5" Bar-B-Kettle; Smokey Joes (A, K); Genesis Silver C (DU); 3 WGAs (EZ, DE, N); 3 SJPs (DT, DU, DR).
"For when democracy becomes tyranny, those of us with rifles still get to vote"