Just to add to everyone one else, always start earlier than you think. It's no fun having people over and stressing about getting the meat done or having guests wait. I know from experience.
I agree with this statement. I was torn at first as well and the 18.5 has done just fine. Like another poster said the only time I would prefer the 22.5 is for rib, but I just don't do them enough to justify it.
I feel your pain. I ordered all new parts for a HM I thought was malfunctioning, built a whole new HM and it turns out the $2 power adapter I bought from Amazon was the issue.