I am going to guess you will love it. They are similar to a backwoods in design. The biggest change for you will be managing a water based smoker (if you choose to fill the pan) vs what you have today. I have done four decent size cooks on my BW Party since I got it recently. Very happy with the results. Moist food shouldn't be a problem.
I was concerned about managing the fire and water in an upright vertical. My smoker has no heat diverter which I read I really should have to slow down water evaporation. But I am getting 10 hours of charcoal burn and about five + hours on the water pan. Not the 18+ hours your eggs can go but very reasonable.
I would buy a humphreys in a heartbeat. I actually bought my party from them which was a refurb. Was more affordable to buy used now. But I see a Humphreys somewhere in. My future! Good luck.
BW Party - UDS - 18.5" WSM - Mini WSM
Red Weber Master Touch- "Old Betsy"
Weber OTS 18" - Weber Genesis
"Yeah, all those things, responsibility, pressure. It`s a bit stressful. I try and come to terms with it by not thinking about it." - Joe Strummer