Remember Cambridge isn't just a total food replacement. You can have food, you can have fizzy drinks...you could even have the odd tipple. Depends which plan you do.
Yes, some do SS but plenty more do 810 and never do shakes only, so if you need your fizzy drinks and want food, go for that.
For maximum loss, I would say SS or SS+, then moving on to 810 if you feel the need for food. A quick go up the plans a couple of weeks before the holidays, which I probably shouldn't suggest as CWP prefer 2 weeks on each plan, but better than suddenly going from SS to 'eat everything' mode.