I am a huge fan of cuff dumps, but I know a lot of divers who dislike them. There are different types, both have advantages and disadvantages.
As a new drysuit diver, the wrist dump is a lot easier to use. As Dusty mentioned, if you raise your arm though, air comes out quickly and easily. However, this can be avoided by closing the valve. As a DS instructor, I enjoy teaching new DS divers in a cuff dump because the students seem to learn buoyancy in a DS a lot easier, because all they have to do is lift their arm and air comes out, much like it does in a BCD.
Seasoft has cuff dump standard on all their suits, and depending on which suit you get, it will be a Si-tech valve. Other manufactures (DUI and Whites for example) give you this as an option if you order a custom suit. I am a fan of the Si-Tech valves. They are easy to maintain and seem to last a lot longer than other brands I have used over the years.
Diving Concepts has an option of a 1 way valve, which is about the size of a quarter. (I am sure other companies do too, however DC is the only one I am familiar with) Unless you are experienced in diving a drysuit, the airbubble in the suit is a bit harder to manage. However, the air comes out very quickly and buoyancy is very simple to maintain, once you figure out how to use the valve. I have one on my DC suit, and it is very nice.
Once you get used to diving dry, and managing the bubble in your suit, you will figure out the easiest way to get out of the shoulder dump and it will become quite easy for you. If you are in the market to purchase a suit, I would suggest you try both to see which is more comfortable for you. It just takes some practice, and a lot of diving
