I did the first StartupWorkaway in Costa Rica. The other 15 founders were awesome (handpicked from 200ish applicants if memory serves). The venue was epic (12,000 square foot villa with 2 pools on a cliff). And it was cheaper than any vacation that I've ever taken (the economies of scale when 15 founders rent a big villa and a chef are pretty amazing). In fact, it was probably cheaper than staying home.
I'd recommend the experience without reservation.