Yes... for the winter i ride a board with more volumn... i personally like a board with alot more volumn when im wearing winter suit. It just makes it easier and I get way more waves... This winter i was riding one of those tuflite boards which really worked well! Im stoked on it... that main thing is to have a board that floats and paddles better- not always just a board with more volumn... ya... drop the 5'8 if your not getting good waves... go for the 6'4 if you already have it... but winters over... so back on the 5'8
I totally agree- its not the board - its the barrel, your form and surfing ability. I love getting shacked on a longboard!!!
I feel like you can't fall on a longboard in the winter though. That much weight being thrown around with you underneath in a nice hollow winter wave seems a little sketchy to me. And taking waves on the head doesn't sound too fun either.
I agree with a lot of what's been said already. Along with the, "it depends on the wave" idea, I can only add that I like a bit more flex in my board when it's super hollow, especially when the bottom is dropping out and you're taking off sort of under the lip. Some added flex will let the board conform to the wave face better, which gives you better rail and fin set. It also give you more overall rocker when you need it, which is when your stuffing yourself into a really tight, curvy pocket.
Lots of factors influence a board's flex pattern... Thickness, stringer, glass schedule, and resin type used are major influences. Foil, length, and bottom/deck contours come after that, IMO, along with the use of rail channels, tail rail patches, etc.