I used a Mamiya C33 and C3 (TLRs) until they were stolen (early 1980's), I replaced them with a pair of Mamiya 645s (one a 1000S), great cameras, superb lenses.

Obviously a folder is lighter but the flexibility of the Mamiya 645 is great for serious photography, mine were used professionally for well over 20 years, they still get used for certain projects.

Ian