Have both Little Buddy and Big Buddy.
Little Buddy is portable and use it in my 1 man Clam Blazer Stealth. Keeps it VERY warm in -25F, almost too hot at over 15 F. Burns through 1 lb of propane in 8-10 hours.
Use Big Buddy and 20# propane tank to heat my large Clam Spearfisher hub with 9ft diameter. I only use it on low or medium. High is just too hot, even at -25F. Also, the Little Buddy would never keep the Hub warm in those conditions.