You don't have to have the water pan in.
I leave it out when I cook wings, otherwise it is in, foiled, half the time with, half the time without water.
Totally up to you. If you like the results you get off of your UDS w/o a pan, you may like using the WSM the same way.
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; 4 22.5" Bar-B-Q-Kettles; 2 18.5" Bar-B-Q-Kettle; 1 Red OTS (H); 3 WGAs (EZ, DE, N); 3 SJPs (DT, DR, DR); 2 Smokey Joes (A, K); Genesis Silver C (DU).
"For when democracy becomes tyranny, those of us with rifles still get to vote"