Refresher courses tend to be much cheaper than taking the whole Open-Water class again. I definitely recommend the refresher, unless you happen to have a very experienced dive-buddy. Two people who haven't dove in a long-time are actually an increased liability on each other.
Even with a few hundred dives and a shorter (6 month) break, I tend to take it easy on my first few dives of the season. I typically starting 15t-30ft deep, verify all my equipment works, practice a few skills, ensure I'm comfortable, etc. It's not anything to do with comfort-level, but rather a sanity, equipment, and safety-check.
